Literature on Glaciology and Ice Sheet Modelling, Digital Elevation Models (DEM) with respect to uncertainty and error modelling, as well as landform detection and general GIS/GIScience issues
This is a dump of my bibtex reference database from my undergoing PhD project. Obviously, there's no claim to being exhaustive here, but I'd of course appreciate any paper suggestions to fhebeler_at_geo.unizh.ch. I'll be happy to include it in this list. Some of the reference formatting might not be perfect, This page is generated using a custom export filter for JabRef, derived from a template from Mark Schenk (Thanks!).
Use the quick search field to look for keywords in all displayed fields, allows plain text and RegExp searches! Some syntax hints:
Use the 'Abstract' and 'BibTeX' links to toggle on/off the according information, where available.
| Author | Year | Title | Journal/Proceedings/etc | Topic | Keywords | DOI/URL |
|---|---|---|---|---|---|---|
| Abe-Ouchi, A., Segawa, T., Yamagishi, T., Saito, F. & Nishimura, T. | 2002 | Topographic effects of the ice sheets on their self maintenance and shaping the climate during the LGM. | American Geophysical Union 2002 Fall Meeting American Geophysical Union | ISM | ISM; LGM; topography; climate; | URL |
| Abstract: Through several studies in the past, it is stated that the cooling at Last Glacial Maximum (LGM) over the NH is caused mainly by the ice sheet existence. It is natural to state a question why and how the ice sheets over Europe and north America have grown and disappeared. To explain the ice sheet growth and termination, there are debates whether the climate was driven by orbital forcing and/or CO2, or how much self-maintenance mechanism of ice sheet worked. In this study, we try to evaluate the main ice sheet - atmosphere feedback, such as ice albedo feedback, elevation - mass balance feedback, stationary wave feedback (through temperature) and transient eddy feedback (through precipitation). Sensitivity experiments are performed using the CCSR/NIES AGCM (T106, 1x1 deg, L20). Additionally a three dimensional thermo-mechanical ice sheet model (Saito and Abe-Ouchi, 2002) is used to diagnose each effect. It is driven with a Degree Day mass balance model forced by AGCM (monthly mean temperature and precipitation). The main conclusions are as following; (1) The ice sheet during the LGM is maintained mostly by albedo feedback and elevation-mass balance feedback. (careful treatment of albedo parameters are needed). (2) Stationary wave effect on temperature is extracted. Its effect is important for the advance in the east part of Laurentide ice sheet and prevents the migration in the Alaska region. (3) Lapse rate is about 5 k/km. (4) Laurentide do help the Fennoscanavia ice sheet to grow in the western part through the transient eddy feedback. (5) Growth of Fennoscandinan ice sheet to the south in the western part is prevented by the stationary wave feedback of Laurentide ice sheet and the presence of itself. | ||||||
BibTeX:
@inproceedings{abe-ouchi2002american,
author = {Abe-Ouchi, Ayako and Segawa, T. and Yamagishi, T. and Saito, F. and Nishimura, T.},
title = {Topographic effects of the ice sheets on their self maintenance and shaping the climate during the LGM.},
booktitle = {American Geophysical Union 2002 Fall Meeting },
year = {2002},
url = {http://cgrg.geog.uvic.ca/abstracts/Abe-OuchiTopographicThrough.html}
}
|
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| Aerts, J. C. J. H., Clarke, K. C. & Keuper, A. D. | 2003 | Testing popular visualization techniques for representing model uncertainty. | Cartography and Geographic Information Science 30 (3) , 249-261 | URL |
||
| Abstract: Many land allocation issues, such as land-use planning, require input from extensive spatial databases and involve complex decision-making. Spatial decision support systems (SDSS) are designed to make these issues more transparent and to support the design and evaluation of land allocation alternatives. In this paper we analyze techniques for visualizing uncertainty of an urban growth model called SLEUTH, which is designed to aid decision-makers in the field of urban planning and fits into the computational framework of an SDSS. Two simple visualization techniques for portraying uncertainty—static comparison and toggling—are applied to SLEUTH results and rendered with different background information and color schemes. In order to evaluate the effectiveness of the two visualization techniques, a web-based survey was developed showing the visualizations along with questions about the usefulness of the two techniques. The web survey proved to be quickly accessible and easy to understand by the participants. Participants in the survey were mainly recruited among planners and decision-makers. They acknowledged the usefulness of portraying uncertainty for decision-making purposes. They slightly favored the static comparison technique over toggling. Both visualization techniques were applied to an urban growth case study for the greater Santa Barbara area in California, USA. | ||||||
BibTeX:
@article{Aerts2003CartGISc,
author = {Aerts, Jeroen C. J. H. and Clarke, Keith C. and Keuper, Alex D.},
title = {Testing popular visualization techniques for representing model uncertainty.},
journal = {Cartography and Geographic Information Science},
year = {2003},
volume = {30},
number = {3},
pages = {249-261},
url = {http://www.ingentaconnect.com/content/acsm/cagis/2003/00000030/00000003/art00003}
}
|
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| Agumya, A. & Hunter, G. J. | 2002 | Responding to the consequences of uncertainty in geographical data. | International Journal of Geographical Information Science 16 (5) , 405-417 | GIS, uncertainty | DOI |
|
| Abstract: The presence of uncertainty in geographical data has the potential to expose users to undesirable consequences in their decision making. Accordingly, our efforts to understand uncertainty seek to ( a ) avoid the use of data that are not suitable for their intended purpose (that is, data whose consequences are unacceptable), ( b ) to reduce any undesirable consequences to an acceptable level, and ( c ) to devise ways of living with undesirable data when the adverse consequences caused by poor data do not alter our ultimate decision choice. To assist this task, we propose an approach where the adverse consequences of uncertainty caused by the use of unsuitable geographical data are expressed in terms of risk. In this paper we first show that risk management offers geographical data users a range of options for responding to the adverse consequences of data uncertainty, and secondly we present and discuss the various risk response options. | ||||||
BibTeX:
@article{Agumya2002IJGIS,
author = {Agumya, Aggrey and Hunter, Gary J.},
title = {Responding to the consequences of uncertainty in geographical data.},
journal = {International Journal of Geographical Information Science},
year = {2002},
volume = {16},
number = {5},
pages = {405-417},
doi = {10.1080/13658810210137031}
}
|
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| Albani, M., Klinkenberg, B., Andison, D. W. & Kimmins, J. P. | 2004 | The choice of window size in approximating topographic surfaces from Digital Elevation Models. | International Journal of Geographical Information Science 18 (6) , 557-593 | DEM | DEM; terrain analysis; topography; surface modelling | DOI |
| Abstract: Quantitative surface analysis through quadratic modelling of Digital Elevation Models (DEMs) is a promising tool for automatically describing the physical environment in ecological studies of terrestrial landscapes. Fundamental topographic variables such as slope, aspect, plan and profile curvature can be simply calculated from the parameters of a conic equation fitted to a DEM window through the least-squares method. The scale of the analysis, defined by the size of the DEM window used to fit the conic equation, affects both the estimated value of the topographic variables and the propagation of elevation errors to derived topographic variables. The least-squares method is amenable to the analytical treatment of the propagation of elevation errors to the derived topographical variables. A general analytical model of error propagation is presented that accounts for the effects of window size and of spatial autocorrelation in elevation errors. The method is based on the Taylor approximation of the least-square fitting equation and allows for the presence of stationary autocorrelation in the elevation errors. In numerical simulations with DEMs from British Columbia, Canada, it is shown that increasing the size of evaluation windows effectively reduces the propagation of elevation errors to the derived topographic variables. However, this was obtained at the expense of topographic detail. A methodology is proposed to evaluate quantitatively the loss of topographic detail through a chi2-test of the corrected residuals in the immediate neighbourhood of the evaluation point. This methodology, in combination with the analytical model of error propagation, can be used to select the scale or range of scales at which to calculate topographic variables from a DEM. | ||||||
BibTeX:
@article{albani2004ijgis,
author = {Albani, M. and Klinkenberg, B. and Andison, D. W. and Kimmins, J. P.},
title = {The choice of window size in approximating topographic surfaces from Digital Elevation Models.},
journal = {International Journal of Geographical Information Science},
year = {2004},
volume = {18},
number = {6},
pages = {557-593},
doi = {10.1080/13658810410001701987}
}
|
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| Alley, R. B., Clark, P. U., Huybrechts, P. & Joughin, I. | 2005 | Ice-Sheet and Sea-Level Changes | Science 310 , 456-460 | ISM | DOI |
|
| Abstract: Future sea-level rise is an important issue related to the continuing buildup of atmospheric greenhouse gas concentrations. The Greenland and Antarctic ice sheets, with the potential to raise sea level ~70 meters if completely melted, dominate uncertainties in projected sea-level change. Freshwater fluxes from these ice sheets also may affect oceanic circulation, contributing to climate change. Observational and modeling advances have reduced many uncertainties related to ice-sheet behavior, but recently detected, rapid ice-marginal changes contributing to sea-level rise may indicate greater ice-sheet sensitivity to warming than previously considered. | ||||||
BibTeX:
@article{Alley2005Science,
author = {Alley, Richard B. and Clark, Peter U. and Huybrechts, Philippe and Joughin, Ian},
title = {Ice-Sheet and Sea-Level Changes},
journal = {Science},
year = {2005},
volume = {310},
pages = {456-460},
doi = {10.1126/science.1114613}
}
|
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| Anandakrishnan, S., Catania, G. A., Alley, R. B. & Horgan, H. J. | 2007 | Discovery of Till Deposition at the Grounding Line of Whillans Ice Stream. | Science 315 (5820) , 1835-1838 | ISM | DOI |
|
| Abstract: We report on the discovery of a grounding-line sedimentary wedge ("till delta") deposited by Whillans Ice Stream, West Antarctica. Our observation is that grounding-line deposition serves to thicken the ice and stabilize the position of the grounding line. The ice thickness at the grounding line is greater than that of floating ice in hydrostatic equilibrium. Thus, the grounding line will tend to remain in the same location despite changes in sea level (until sea level rises enough to overcome the excess thickness that is due to the wedge). Further, our observation demonstrates the occurrence of rapid subglacial erosion, sediment transport by distributed subglacial till deformation, and grounding-line sedimentation, which have important implications for ice dynamics, numerical modeling of ice flow, and interpretation of the sedimentation record. | ||||||
BibTeX:
@article{Anandakrishnan2007Science,
author = {Anandakrishnan, Sridhar and Catania, Ginny A. and Alley, Richard B. and Horgan, Huw J.},
title = {Discovery of Till Deposition at the Grounding Line of {Whillans} Ice Stream.},
journal = {Science},
year = {2007},
volume = {315},
number = {5820},
pages = {1835-1838},
doi = {10.1126/science.1138393}
}
|
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| Anderson, J. B., Shipp, S. S., Lowe, A. L., Smith Wellner, J. & Mosola, A. B. | 2002 | The Antarctic Ice Sheet during the Last Glacial Maximum and its subsequent retreat history: a review. | Quaternary Science Reviews 21 , 49-70 | ISM | Antarctica; LGM; ice sheet; review; modelling; | DOI |
| Abstract: An emerging body of evidence from studies of the last glacial/interglacial cycle suggests that the East and West Antarctic ice sheets have not advanced and retreated in concert. The West Antarctic ice sheet advanced to the outer shelf in most regions during the Last Glacial Maximum (LGM). The retreat from the shelf commenced shortly after the LGM and continued into the late Holocene. The West Antarctic Ice Sheet in Ross and Amundsen seas slid across a deforming bed, at least during the final phases of extended glaciation. This implies that at this time the ice sheet had a low profile. Differences in the number and locations of grounding-zone wedges and smaller grounding zone features from trough to trough imply that individual West Antarctic Ice Sheet ice streams retreated episodically. Details concerning the expansion, retreat, and behavior of the East Antarctic Ice Sheet (EAIS) are more sparse. The picture emerging is that the EAIS did not expand to the continental shelf edge during the LGM; rather, it achieved a maximum extent of a mid-shelf position in some locations, while in other areas the ice terminus was situated near its present location. The timing of retreat along sectors within the EAIS appears diachronous, and in places occurred prior to the LGM. The Antarctic Peninsula shelf contained considerably more ice during the LGM than previously proposed. The results presented in this paper support more recent published ice-sheet models that call for greater contributions of melting ice from West Antarctica, including the Antarctic Peninsula, to the post-glacial rise in sea level. | ||||||
BibTeX:
@article{Anderson2002QSR,
author = {Anderson, John B. and Shipp, Stephanie S. and Lowe, Ashley L. and Smith Wellner, Julia and Mosola, Amanda B.},
title = {The Antarctic Ice Sheet during the Last Glacial Maximum and its subsequent retreat history: a review.},
journal = {Quaternary Science Reviews},
year = {2002},
volume = {21},
pages = {49-70},
doi = {10.1016/S0277-3791(01)00083-X}
}
|
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| Anderson, J. L. | 1996 | A Method for Producing and Evaluating Probabilistic Forecasts from Ensemble Model Integrations. | Journal of Climate 9 (7) , 1518-1530 | DOI |
||
| Abstract: The binned probability ensemble (BPE) technique is presented as a method for producing forecasts of the probability distribution of a variable using an ensemble of numerical model integrations. The ensemble forecasts are used to partition the real line into a number of bins, each of which has an equal probability of containing the “true� forecast. The method is tested for both a simple low-order dynamical system and a general circulation model (GCM) forced with observed sea surface temperatures (an ensemble of Atmospheric Model Intercomparison Project integrations). The BPE method can also be used to calculate the probability that probabilistic ensemble forecasts are consistent with the verifying observations. The method is not sensitive to the fact that the characteristics of the forecast probability distribution may change drastically for different initial condition (or boundary condition) probability distributions. For example, the method is capable of evaluating whether the variance of a set of ensemble forecasts is consistent with the verifying observed variance. Applying the method to the ensemble of boundary-forced GCM integrations demonstrates that the GCM produces probabilistic forecasts with too little variability for upper-level dynamical fields. Operational weather prediction centers including the U.K. Meteorological Office, the European Centre for Medium-Range Forecasts, and the National Centers for Environmental Prediction have been applying this method, referred to by them as Talagrand diagrams, to the verification of operational ensemble predictions. The BPE method only evaluates the consistency of ensemble predictions and observations and should be used in conjunction with additional verification tools to provide a complete assessment of a set of probabilistic forecasts. | ||||||
BibTeX:
@article{Anderson1996JC,
author = {Anderson, Jeffrey L.},
title = {A Method for Producing and Evaluating Probabilistic Forecasts from Ensemble Model Integrations.},
journal = {Journal of Climate},
year = {1996},
volume = {9},
number = {7},
pages = {1518-1530},
doi = {10.1175/1520-0442(1996)009<1518:AMFPAE>2.0.CO;2}
}
|
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| Anselin, L. | 1995 | Local Indicators of Spatial Association - LISA. [BibTeX] |
Geographical Analysis 27 (2) , 93-115 | uncertainty | DEM; Analysis; Moran; Geary uncertainty; autocorrelation | |
BibTeX:
@article{Anselin1995GAnalys,
author = {Anselin, Luc},
title = {Local Indicators of Spatial Association - {LISA.}},
journal = {Geographical Analysis},
year = {1995},
volume = {27},
number = {2},
pages = {93-115}
}
|
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| Armstrong, R. N. & Martz, L. W. | 2003 | Topographic parameterization in continental hydrology: a study in scale. | Hydrological Processes 17 (18) , 3763-3781 | subgrid; DEM | DOI URL |
|
| Abstract: Digital elevation models (DEMs) are useful and popular tools from which topographic parameters can be quickly and efficiently extracted for various hydrologic applications. DEMs coupled with automated methods for extracting topographic information provide a powerful means of parameterizing hydrologic models over a wide range of scales. However, choosing appropriate DEM scales for particular hydrologic modelling applications is limited by a lack of understanding of the effects of scale and grid resolution on land-surface representation. The scale effects of aggregation on square-grid DEMs of two continental-scale basins are examined. Base DEMs of the Mackenzie and Missouri River basins are extracted from the HYDRO1k DEM of North America. Successively coarser grids of 2, 4, 8, 64 km were generated from the base DEMs using simple linear averaging. TOPAZ (Topographic Parameterization) was applied to the base and aggregated DEMs using constant critical source area and minimum source channel length values to extract topographic variables at varying scales or resolutions. The effects of changing DEM resolution are examined by considering changes in the spatial distribution and statistical properties of selected topographic variables of hydrological importance. The effects of increasing grid size on basin and drainage network delineation, and derived topographic variables, tends to be non-linear. In particular, changes in overall basin extent and drainage network configuration make it impractical to apply a simple scaling function to estimate variable values for fine-resolution DEMs from those derived from coarse-resolution DEMs. Results also suggest the resolution to which a DEM can be reduced by aggregation and still provide useful topographic information for continental-scale hydrologic modelling is that at which the mean hydraulic slope falls to approximately 1%. In this study, that generally occurred at a resolution of about 10 km. | ||||||
BibTeX:
@article{Armstrong2003HP,
author = {Armstrong, Robert N. and Martz, Lawrence W.},
title = {Topographic parameterization in continental hydrology: a study in scale.},
journal = {Hydrological Processes},
year = {2003},
volume = {17},
number = {18},
pages = {3763-3781},
url = {http://www3.interscience.wiley.com/cgi-bin/abstract/106571455/ABSTRACT},
doi = {10.1002/hyp.1352}
}
|
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| Arrell, K., Fisher, P. F., Tate, N. J. & Bastin, L. | 2007 | A fuzzy c-means classification of elevation derivatives to extract the morphometric classification of landforms in Snowdonia, Wales. | Computers & Geoscience 33 (10) , 1366-1381 | DEM, uncertainty | Landforms; Morphometric classes; Fuzzy; Digital elevation model; Resolution; Snowdonia | DOI |
| Abstract: The increasing global coverage of high resolution/large-scale digital elevation data has allowed the study of geomorphological form to receive renewed attention by providing accessible datasets for the characterisation and quantification of land surfaces. Digital elevation models (DEMs) provide quantitative elevation data, but it is the characterisation and extraction of geomorphologically significant measures (morphometric indices) from these raw data that form more informative and useful datasets. Common to many geographical measures, morphometric measures derived from DEMs are dependent on the scale of observation. This paper reports results of employing a fuzzy c-means classification for a sample DEM from Snowdonia, Wales, with a number of morphometric measures at different resolutions as input, and morphometric classification of landforms at each resolution as output. The classifications reveal that different landscape components or morphometric classes are important at different resolutions, and that morphometric classes exhibit resolution dependency in their geographical extents. Examination of the scale dependency and behaviour of morphometric classifications of landforms at different resolutions provides a fuller and more holistic view of the classes present than a single-scale analysis. | ||||||
BibTeX:
@article{Arrell2007CG,
author = {Arrell, K.E. and Fisher, Peter F. and Tate, Nicholas J. and Bastin, L.},
title = {A fuzzy c-means classification of elevation derivatives to extract the morphometric classification of landforms in {Snowdonia, Wales}.},
journal = {Computers \& Geoscience},
year = {2007},
volume = {33},
number = {10},
pages = {1366-1381},
doi = {10.1016/j.cageo.2007.05.005}
}
|
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| Atkinson, P. M. | 2002 | Surface Modelling: What's the Point? [BibTeX] |
Transactions in GIS 6 (1) , 1-4 | uncertainty | surface modelling; DEM; uncertainty; | DOI |
BibTeX:
@article{Atkinson2002TIGIS,
author = {Atkinson, Peter M.},
title = {Surface Modelling: What's the Point?},
journal = {Transactions in GIS},
year = {2002},
volume = {6},
number = {1},
pages = {1-4},
doi = {10.1111/1467-9671.00090}
}
|
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| Bamber, J. L. & Bindschadler, R. A. | 1997 | An improved elevation dataset for climate and ice-sheet modelling: validation with satellite imagery. [BibTeX] |
Annals of Glaciology 25 , 439-444 | ; Ice sheet model; satellite data; | ||
BibTeX:
@article{Bamber1997AGla,
author = {Bamber, J. L. and Bindschadler, R. A.},
title = {An improved elevation dataset for climate and ice-sheet modelling: validation with satellite imagery.},
journal = {Annals of Glaciology},
year = {1997},
volume = {25},
pages = {439-444}
}
|
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| Behrens, T., Förster, H., Scholten, T., Steinrücken, U., Spies, E. & Goldschmitt, M. | 2005 | Digital Soil Mapping using Artificial Neural Networks. | Journal of Plant Nutrition and Soil Science 168 , 21-33 | DOI |
||
| Abstract: In the context of a growing demand of high-resolution spatial soil information for environmental planning and modeling, fast and accurate prediction methods are needed to provide high-quality digital soil maps. Thus, this study focuses on the development of a methodology based on artificial neural networks (ANN) that is able to spatially predict soil units. Within a test area in Rhineland-Palatinate (Germany), covering an area of about 600 km2, a digital soil map was predicted. Based on feed-forward ANN with the resilient backpropagation learning algorithm, the optimal network topology was determined with one hidden layer and 15 to 30 cells depending on the soil unit to be predicted. To describe the occurrence of a soil unit and to train the ANN, 69 different terrain attributes, 53 geologic-petrographic units, and 3 types of land use were extracted from existing maps and databases. 80% of the predicted soil units (n = 33) showed training errors (mean square error) of the ANN below 0.1, 43% were even below 0.05. Validation returned a mean accuracy of over 92% for the trained network outputs. Altogether, the presented methodology based on ANN and an extended digital terrain-analysis approach is time-saving and cost effective and provides remarkable results. | ||||||
BibTeX:
@article{Behrens2005JPNSS,
author = {Behrens, Thorsten and F\"orster, Helga and Scholten, Thomas and Steinr\"ucken, Ulrich and Spies, Ernst-Dieter and Goldschmitt, Michael},
title = {Digital Soil Mapping using Artificial Neural Networks.},
journal = {Journal of Plant Nutrition and Soil Science},
year = {2005},
volume = {168},
pages = {21-33},
doi = {10.1002/jpln.200421414}
}
|
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| Benn, D. I. & Evans, D. J. | 1998 | Glaciers and Glaciation. [BibTeX] |
Arnold, London | ISM | ISM; glaciology; | |
BibTeX:
@book{Benn1998book,
author = {Benn, Douglas I. and Evans, David J.A.},
title = {Glaciers and Glaciation.},
publisher = {Arnold, London},
year = {1998}
}
|
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| Bertin, J. | 1983 | Semiology of graphics: Diagrams, networks, maps. [BibTeX] |
University of Wisconsin Press, Madison, Wisconsin. | |||
BibTeX:
@book{Bertin1983book,
author = {Bertin, J.},
title = {Semiology of graphics: Diagrams, networks, maps.},
publisher = {University of Wisconsin Press, Madison, Wisconsin.},
year = {1983}
}
|
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| Beven, K. | 2007 | Towards integrated environmental models of everywhere: uncertainty, data and modelling as a learning process | Hydrology and Earth System Sciences 11 (1) , 460--467 | URL |
||
| Abstract: Developing integrated environmental models of everywhere such as are demanded by the requirements of, for example, implementing the Water Framework Directive in Europe, is constrained by the limitations of current understanding and data availability. The possibility of such models raises questions about system design requirements to allow modelling as a learning and data assimilation process in the representation of places, which might well be treated as active objects in such a system. Uncertainty in model predictions not only poses issues about the value of different types of data in characterising places and constraining predictive uncertainty but also about how best to present the pedigree of such uncertain predictions to users and decision-makers. | ||||||
BibTeX:
@article{Beven2007HESS,
author = {Beven, K.},
title = {Towards integrated environmental models of everywhere: uncertainty, data and modelling as a learning process},
journal = {Hydrology and Earth System Sciences},
year = {2007},
volume = {11},
number = {1},
pages = {460--467},
url = {http://www.hydrol-earth-syst-sci.net/11/460/2007/}
}
|
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| Beven, K. & Kirkby, M. | 1979 | A physically based variable contribution area model of basin hydrology. | Hydrological Science Bulletin 24 , 43-69 | URL |
||
| Abstract: A hydrological forecasting model is presented that attempts to combine the important distributed effects of channel network topology and dynamic contributing areas with the advantages of simple lumped parameter basin models. Quick response flow is predicted from a storage/contributing area relationship derived analytically from the topographic structure of a unit within a basin. Average soil water response is represented by a constant leakage infiltration store and an exponential subsurface water store. A simple non-linear routing procedure related to the link frequency distribution of the channel network completes the model and allows distinct basin sub-units, such as headwater and sideslope areas to be modelled separately. The model parameters are physically based in the sense that they may be determined directly by measurement and the model may be used at ungauged sites. Procedures for applying the model and tests with data from the Crimple Beck basin are described. Using only measured and estimated parameter values, without optimization, the model makes satisfactory predictions of basin response. The modular form of the model structure should allow application over a range of small and medium sized basins while retaining the possibility of including more complex model components when suitable data are available. | ||||||
BibTeX:
@article{Beven1979HSB,
author = {Beven, K.J. and Kirkby, M.J.},
title = {A physically based variable contribution area model of basin hydrology.},
journal = {Hydrological Science Bulletin},
year = {1979},
volume = {24},
pages = {43-69},
url = {http://www.cig.ensmp.fr/%7eiahs/hsj/hsj241.htm}
}
|
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| Beven, K. J. & Moore, I. D. | 1992 | Terrain Analysis and Distributed Modelling in Hydrology. [BibTeX] |
John Wiley & Sons, Inc., Chichester | DEM | terrain analysis; hydrology; modelling; | |
BibTeX:
@book{beven1992book,
author = {Beven, K. J. and Moore, I. D.},
title = {Terrain Analysis and Distributed Modelling in Hydrology.},
publisher = {John Wiley \& Sons, Inc., Chichester},
year = {1992}
}
|
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| Bindschadler, R. & Gore, R. | 1982 | A time-dependent ice-sheet model - preliminary results. | Journal of Geophysical Research - Oceans and Atmospheres 87 (NC12) , 9675-9685 | ISM | ice sheet model; flow model; basal water pressure; | |
| Abstract: A numerical model of ice sheet flow is developed, and preliminary results are described. This model includes vertical resolution of temperature, stress, and strain rate which represents a considerable improvement over previous vertically averaged ice sheet models. The model follows the flow of ice along a flow line within an ice sheet drainage basin. Longitudinal stresses and basal sliding are included. Basal sliding is dependent on the base shear stress and a specified distribution of basal water pressure. The numerical methods used to solve the coupled set of stress and velocity equations for the static and time-evolutionary cases are discussed. A steady state profile simulating an ice stream is calculated for a particular set of input parameters, and changes in the profile are examined for different choices of parameters. Preliminary studies of response behavior are completed using a simplified ice sheet geometry with a fixed terminus or grounding line. The results of these studies illustrate ice sheet thinning in response to a lowered sea level or to a reduction in the extent of ice rises (or pinning points) within ice shelves. | ||||||
BibTeX:
@article{bindschadler1982jgr,
author = {Bindschadler, R.A. and Gore, R.},
title = {A time-dependent ice-sheet model - preliminary results.},
journal = {Journal of Geophysical Research - Oceans and Atmospheres},
year = {1982},
volume = {87},
number = {NC12},
pages = {9675-9685}
}
|
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| Bintanja, R., van de Wal, R. & Oerlemans, J. | 2002 | Global ice volume variations through the last glacial cycle simulated by a 3-D ice-dynamical model. | Quaternary International 95 96 , 11-23 | ISM | ice sheet model; LGM; ISM; | URL |
| Abstract: A coupled ice sheet�ice shelf�bedrock model was run at 20km resolution to simulate the evolution of global ice cover during the last glacial cycle. The mass balance model uses monthly mean temperature and precipitation as input and incorporates the albedo�mass balance feedback. The model is forced by the GRIP and Vostok�derived temperature records (and by sea level and solar radiation variations), which are distributed spatially and seasonally. Model simulations show that at the last glacial maximum (LGM) a volume of ice representing about 65m of sea level equivalent is stored on the Eurasian continent, whereas North America stores 42 m. The other regions (Greenland, Tibet, South-America and Antarctica) contribute about 17m to global sea level lowering at the LGM compared to present day. Sensitivity experiments show that the ice volumes of the Eurasian and North American ice sheets are particularly sensitive to summer temperature changes. Finally, the timing and mechanism of grounded ice formation and expansion for the last glacial were studied for the Eurasian and North American continents. Ice sheet formation begins at 118 kyr BP in the Barents and Kara Sea region, over Baffin Island and in the high Cordilleran Range following a 41C cooling. Alternating regions of ice sheet expansion by direct snowfall, ice flow and grounding of ice shelves can be identified. These relate to specific geomorphological traces, and may as such help in model validation. | ||||||
BibTeX:
@article{bintanja2002qi,
author = {Bintanja, R. and van de Wal, R.S.W. and Oerlemans, J.},
title = {Global ice volume variations through the last glacial cycle simulated by a 3-D ice-dynamical model.},
journal = {Quaternary International},
year = {2002},
volume = {95 96},
pages = {11-23},
url = {http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6VGS-45J8YCC-1-1H&_cdi=6046&_orig=browse&_coverDate=09%2F30%2F2002&_sk=999039999&view=c&wchp=dGLbVtb-zSkzV&_acct=C000049009&_version=1&_userid=946230&md5=9655b9c96fdc13e2355a9840d5a4e0c6&ie=f.pdf}
}
|
||||||
| Blatter, H. | 1995 | Velocity and stress fields in grounded glaciers: A simple algorithm for including deviatoric stress gradients. | Journal of Glaciology 41 , 333-343 | ISM | ||
| Abstract: A new and efficient algorithm for computing the three-dimensional stress and velocity fields in grounded glaciers includes the role of deviatoric stress gradients. A consistent approximation of first order in the aspect of ratio of the ice mass gives a set of eight field equations for the five stress and three velocity components and the corresponding boundary conditions. A coordinate transformation mapping the local ice thickness on to unity and approximating the derivatives in the horizontal direction by centered finite-differences yields five ordinary differential and three algebraic equations. This allows use of the method of lines, starting the integration with prescribed stress and velocity components at the base, and a simple iteration procedure converges rapidly. The algorithm can be used for a wide range of stress-strain-rate relations, as long as strain only depends on deviatoric and shear stresses and on temperature. Sensitivity tests using synthetic and realistic ice geometries show the relevance of normal deviatoric stresses in the solutions for the velocity components even for ice sheets. Stress and velocity fields may deviate substantially from the widely used shallow-ice approximation. | ||||||
BibTeX:
@article{Blatter1995JGla,
author = {Blatter, Heinz},
title = {Velocity and stress fields in grounded glaciers: A simple algorithm for including deviatoric stress gradients.},
journal = {Journal of Glaciology},
year = {1995},
volume = {41},
pages = {333-343}
}
|
||||||
| Boulton, G., Hulton, N. & Vautravers, M. | 1995 | Ice-sheet models as tools for palaeoclimatic analysis: the example of the European ice sheet through the last glacial cycle. [BibTeX] |
Annals of Glaciology 21 , 103-110 | ISM | ||
BibTeX:
@article{Boulton1995AGla,
author = {Boulton, G.S. and Hulton, Nicholas and Vautravers, M.},
title = {Ice-sheet models as tools for palaeoclimatic analysis: the example of the European ice sheet through the last glacial cycle.},
journal = {Annals of Glaciology},
year = {1995},
volume = {21},
pages = {103-110}
}
|
||||||
| Boulton, G. & Payne, A. | 1992 | Simulation of the European ice sheet through the last glacial cycle and prediction of future glaciation. [BibTeX] |
(SKB 93-14) Swedish Nuclear Fuel and Waste Management Co. | ISM | ISM; LGM; | |
BibTeX:
@techreport{boulton1992tech,
author = {Boulton, G.S. and Payne, Anthony},
title = {Simulation of the {European} ice sheet through the last glacial cycle and prediction of future glaciation.},
year = {1992},
number = {SKB 93-14}
}
|
||||||
| Box, J. E., Bromwich, D. H., Veenhuis, B. A., Bai, L., Wang, S., Stroeve, J. C., Haran, T., Rogers, J. C. & Steffen, K. | 2006 | Greenland Ice Sheet Surface Mass Balance Variability (1988-2004) from Calibrated Polar MM5 Output. | Journal of Climate 19 (12) , 2783-2800 | ISM | ablation; ISM; Greenland; mass balance; | DOI |
| Abstract: Regional climate model runs using the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesocale Model modified for use in polar regions (Polar MM5), calibrated by independent in situ observations, demonstrate coherent regional patterns of Greenland ice sheet surface mass balance (SMB) change over a 17-yr period characterized by warming (1988–2004). Both accumulation and melt rates increased, partly counteracting each other for an overall negligible SMB trend. However, a 30% increase in meltwater runoff over this period suggests that the overall ice sheet mass balance has been increasingly negative, given observed meltwater-induced flow acceleration. SMB temporal variability of the whole ice sheet is best represented by ablation zone variability, suggesting that increased melting dominates over increased accumulation in a warming scenario. The melt season grew in duration over nearly the entire ablation zone by up to 40 days, 10 days on average. Accumulation area ratio decreased by 3%. Albedo reductions are apparent in five years of the Moderate Resolution Imaging Spectroradiometer (MODIS) derived data (2000–04). The Advanced Very High Resolution Radiometer (AVHRR)-derived albedo changes (1988–99) were less consistent spatially. A conservative assumption as to glacier discharge and basal melting suggests an ice sheet mass loss over this period greater than 100 km3 yr−1, framing the Greenland ice sheet as the largest single glacial contributor to recent global sea level rise. Surface mass balance uncertainty, quantified from residual random error between model and independent observations, suggests two things: 1) changes smaller than approximately 200 km3 yr−1 would not satisfy conservative statistical significance thresholds (i.e., two standard deviations) and 2) although natural variability and model uncertainty were separated in this analysis, the magnitude of each were roughly equivalent. Therefore, improvements in model accuracy and analysis of longer periods (assuming larger changes) are both needed for definitive mass balance change assessments. | ||||||
BibTeX:
@article{Box2006JC,
author = {Box, Jason E. and Bromwich, David H. and Veenhuis, Bruce A. and Bai, Le-Sheng and Wang, Sheng-Hung and Stroeve, Julienne C. and Haran, T and Rogers, Jeffrey C. and Steffen, Konrad},
title = {{Greenland} Ice Sheet Surface Mass Balance Variability (1988-2004) from Calibrated Polar {MM5} Output.},
journal = {Journal of Climate},
year = {2006},
volume = {19},
number = {12},
pages = {2783-2800},
doi = {10.1175/JCLI3738.1}
}
|
||||||
| Braithwaite, R. | 1995 | Positive degree-day factors for ablation on the Greenland ice sheet studied by energy-balance modelling. [BibTeX] |
Journal of Glaciology 41 (137) , 153-159 | ISM | ISM; climate model; glaciology; | |
BibTeX:
@article{braithwaite1995jgla,
author = {Braithwaite, R.J.},
title = {Positive degree-day factors for ablation on the {Greenland} ice sheet studied by energy-balance modelling.},
journal = {Journal of Glaciology},
year = {1995},
volume = {41},
number = {137},
pages = {153-159}
}
|
||||||
| Brock, B. W. & Arnold, N. S. | 2000 | A spreadsheet-based (Microsoft Excel) point surface energy balance model for glacier and snow melt studies. | Earth Surface Processes and Landforms 25 (6) , 649-658 | ISM | DOI |
|
| Abstract: This paper describes a point surface energy balance model which runs within the Microsoft Excel spreadsheet package. The study incorporates a large amount of previous energy balance work and presents it in a useable form. The core model calculates the net shortwave and longwave radiation fluxes, the turbulent sensible and latent heat fluxes and the surface melt rate at a point on a melting ice or snow surface, from hourly inputs of incoming shortwave radiation, vapour pressure, air temperature and wind speed data. The latitude, longitude, slope angle, aspect, elevation, local temperature lapse rate, albedo and aerodynamic roughness of the study site, and the elevation of the meteorological station, can all be specified in the model. An output file containing the hourly and daily rates, and the totals of the energy fluxes is generated. The main advantages of the model are: first, that it requires only a PC or laptop computer running standard Microsoft Windows software, enabling it to be used at a desktop or in the field; and second, that it can be adapted quickly to different sites, meteorological data formats and other application requirements. Model calculations are compared with measured surface melt rates at five points on Haut Glacier d'Arolla, Switzerland, over a 115 day ablation period. Allowing for differences in shading between the meteorological station and the glacier, the root mean square error of the calculated melt rates is 2.0 mm day-1 water equivalent melt (mean error +1.2 mm day-1), for measured melt rates in the range 23 to 42 mm day-1 water equivalent melt. | ||||||
BibTeX:
@article{Brock2000ESPL,
author = {Brock, Ben W. and Arnold, Neil S.},
title = {A spreadsheet-based ({Microsoft Excel}) point surface energy balance model for glacier and snow melt studies.},
journal = {Earth Surface Processes and Landforms},
year = {2000},
volume = {25},
number = {6},
pages = {649-658},
doi = {10.1002/1096-9837(200006)25:6<649::AID-ESP97>3.0.CO;2-U}
}
|
||||||
| Browne, O. | 2004 | Improving global glacier modelling by the inclusion of parameterised subgrid hypsometry within a three-dimensional, dynamical ice sheet model. [BibTeX] |
Department of Mathematics, University of Reading | |||
BibTeX:
@mastersthesis{Browne2004msc,
author = {Browne, O.J.H.},
title = {Improving global glacier modelling by the inclusion of parameterised subgrid hypsometry within a three-dimensional, dynamical ice sheet model.},
school = {Department of Mathematics, University of Reading},
year = {2004}
}
|
||||||
| Budd, W. & Jenssen, D. | 1975 | Numerical modelling of glacier systems [BibTeX] |
IAHS Publications 104 , 257-291 | ISM | ||
BibTeX:
@article{Budd1975IAHS,
author = {Budd, W.F. and Jenssen, D.},
title = {{Numerical modelling of glacier systems}},
journal = {IAHS Publications},
year = {1975},
volume = {104},
pages = {257-291}
}
|
||||||
| Budd, W., Jenssen, D. & Smith, I. | 1984 | A three-dimensional time-dependent model of the West Antarctic Ice Sheet. [BibTeX] |
Annals of Glaciology 5 , 29-36 | ISM | Ice sheet model; data; antarctica; | |
BibTeX:
@article{budd1984agla,
author = {Budd, W.F. and Jenssen, D. and Smith, I.N.},
title = {A three-dimensional time-dependent model of the West Antarctic Ice Sheet.},
journal = {Annals of Glaciology},
year = {1984},
volume = {5},
pages = {29-36}
}
|
||||||
| Budd, W. & Smith, I. | 1985 | The state of balance of the Antarctic Ice Sheet. [BibTeX] |
Glaciers, ice sheets and sea level: effect of a CO$_2$ induced climatic change. US DOE Office of Energy Research , 172-177 | ISM | ISM; climate model; | |
BibTeX:
@incollection{budd1985in_usdoe,
author = {Budd, W.F. and Smith, I.N.},
title = {The state of balance of the Antarctic Ice Sheet. },
booktitle = {Glaciers, ice sheets and sea level: effect of a CO$_2$ induced climatic change.},
publisher = {US DOE Office of Energy Research},
year = {1985},
volume = {DOE/ER/60235-1},
pages = {172-177}
}
|
||||||
| Budd, W. & Smith, I. | 1981 | The growth and retreat of ice sheets in response to orbital radiation changes. [BibTeX] |
IAHS 79 , 58-75 | ISM | ISM; climate; climate model; | |
BibTeX:
@article{budd1981IAHS,
author = {Budd, W.F. and Smith, I.N.},
title = {The growth and retreat of ice sheets in response to orbital radiation changes.},
journal = {IAHS},
year = {1981},
volume = {79},
pages = {58-75}
}
|
||||||
| Burrough, P. A., van Gaans, P. F. M. & Hootsmans, R. | 1997 | Continuous classification in soil survey: spatial correlation, confusion and boundaries. | Fuzzy Sets in Soil Science Geoderma 77 (2-4) , 115-135 | landscape morphometry | DOI |
|
| Abstract: This article traces the development of conceptual paradigms of soil classification and mapping from the pre-1960's model of crisp classes in attribute space linked to crisply delineated mapping units in geographical space, to modem approaches using fuzzy classification and geostatistical interpolation for simultaneously handling continuous variation in both attributes and location. Continuous classification yields a separate map of class membership values for every class the dominance of any class at each location can be expressed by a confusion index, CI. If spatial correlation is strong, zones of high CI are concentrated in narrow geographical transition zones between locally dominant classes: these zones can be refined to delineate automatically classspecific boundaries. If spatial correlation in membership values is weak then broad zones of large values of CI occur all over the map. Simulation modelling and two case studies demonstrate that contiguity in geographical space is more important for successful mapping than attribute class compactness. The studies show that soil information systems must take the spatial aspects of soil variation into account; further improvements in identifying and mapping significant soil groupings should be possible using numerical models of soil processes together with the methods presented here. | ||||||
BibTeX:
@article{Burrough1997Geoderma,
author = {Burrough, P. A. and van Gaans, P. F. M. and Hootsmans, R.},
title = {Continuous classification in soil survey: spatial correlation, confusion and boundaries.},
booktitle = {Fuzzy Sets in Soil Science},
journal = {Geoderma},
year = {1997},
volume = {77},
number = {2-4},
pages = {115-135},
doi = {10.1016/S0016-7061(97)00018-9}
}
|
||||||
| Burrough, P. A., van Gaans, P. F. M. & MacMillan, R. A. | 2000 | High-resolution landform classification using fuzzy k-means. | Fuzzy Sets and Systems 113 (1) , 37-52 | DEM, uncertainty | Fuzzy k-means; Fuzzy sets; Digital elevation models; Landform classification; Geographical information systems | DOI |
| Abstract: Previous attempts to devise automated methods of landscape classification have been frustrated by computational issues related to the size of the data set and the fact that most automated classification methods create discrete classes while ‘natural’ interpreted landscape units often have overlapping property sets. Methods of fuzzy k-means have been used by other workers to overcome the problem of class overlap but their usefulness maybe reduced when data sets are large and when the data include artefacts introduced by the derivation of landform attributes from gridded digital elevation models.This paper presents ways to overcome these limitations using spatial sampling methods, statistical modelling of the derived stream topology, and fuzzy k-means using the Distance metric. Using data from Alberta, Canada, and the French pre-Alps it is shown how these methods may easily create meaningful, spatially coherent land form classes from high resolution gridded DEMs. | ||||||
BibTeX:
@article{Burrough2000FSS,
author = {Burrough, Peter A. and van Gaans, P. F. M. and MacMillan, Robert A.},
title = {High-resolution landform classification using fuzzy k-means.},
journal = {Fuzzy Sets and Systems},
year = {2000},
volume = {113},
number = {1},
pages = {37-52},
doi = {10.1016/S0165-0114(99)00011-1}
}
|
||||||
| Burrough, P. A. & McDonnell, R. A. | 1998 | Principles of Geographic Information Systems. [BibTeX] |
Oxford University Press, Oxford | GIS | GIS; | |
BibTeX:
@book{Burrough1998,
author = {Burrough, Peter A. and McDonnell, R. A.},
title = {Principles of Geographic Information Systems.},
publisher = {Oxford University Press, Oxford},
year = {1998}
}
|
||||||
| Buttenfield, B. P. | 2000 | Mapping Ecological Uncertainty. [BibTeX] |
Spatial Uncertainty in Ecology. Springer, Berlin , 116-132 | GIS, uncertainty | URL |
|
BibTeX:
@incollection{Buttenfield2000inbook,
author = {Buttenfield, Barbara P.},
title = {Mapping Ecological Uncertainty.},
booktitle = {Spatial Uncertainty in Ecology.},
publisher = {Springer, Berlin},
year = {2000},
pages = {116-132},
url = {http://www.colorado.edu/geography/babs/papers/NCEAS2000reprint.pdf}
}
|
||||||
| Buttenfield, B. P. | 1993 | Representing Data Quality. | Cartographica 30 (2-3) , 1-7 | uncertainty | DOI |
|
| Abstract: Information on data quality is important for effective use of GIS data. It impacts the credibility of data representation and the confidence that is attached to data interpretations. It impacts the reliability of interpretations and thus decision making based on GIS modeling and data exploration. A number of impediments to representing data quality can be cited, including impediments to definition and assessment, to attribution in a database, and to graphical depiction. This paper elaborates on impediments to representing data quality. The discussion provides a window through which the complexity of representing data quality may be viewed, and to introduce current research efforts and avenues for further research addressing each impediment. | ||||||
BibTeX:
@article{Buttenfield1993Cartographica,
author = {Buttenfield, Barbara P.},
title = {Representing Data Quality.},
journal = {Cartographica},
year = {1993},
volume = {30},
number = {2-3},
pages = {1-7},
doi = {10.3138/232H-6766-3723-5114}
}
|
||||||
| Calov, R. & Marsi, I. | 1998 | Simulations of the Northern Hemisphere through the last glacial-interglacial cycle with a vertically integrated and a three-dimensional thermomechanical ice-sheet model coupled to a climate model. [BibTeX] |
Annals of Glaciology 27 , 169-176 | ISM | ISM; LGM; climate model; | |
BibTeX:
@article{calov1998agla,
author = {Calov, R and Marsi, I.},
title = {Simulations of the Northern Hemisphere through the last glacial-interglacial cycle with a vertically integrated and a three-dimensional thermomechanical ice-sheet model coupled to a climate model.},
journal = {Annals of Glaciology},
year = {1998},
volume = {27},
pages = {169-176}
}
|
||||||
| Calov, R., Savvin, A., Greve, R., Hansen, I. & Hutter, K. | 1998 | Simulation of the Antarctic ice sheet with a three-dimensional polythermal ice-sheet model, in support of the EPICA project. | Annals of Glaciology 27 , 201-206 | ISM, subgrid | URL |
|
| Abstract: The modern dynamic and thermodynamic state of the entire Antarctic ice sheet is computed for a 242 200 year paleoclimatic simulation with the three-dimensional polythermal ice-sheet model SICOPOLIS. The simulation is driven by a climate history derived from the Vostok ice core and the SPECMAP sea-level record. In a 872 km x 436 km region in western Dronning Maud Land (DML), where a deep ice core is planned for EPICA, new high-resolution ice-thickness data are used to compute an improved bedrock topography and a locally refined numerical grid is applied which extends earlier work (Calov and others, 1998). The computed fields of basal temperature, age and shear deformation, together with the measured accumulation rates, give valuable information for the selection of a drill site suitable for obtaining a high-resolution climate record for the last glacial cycle. Based on these results, a possible drill site at 73°59" S, 00°00" E is discussed, for which the computed depth profiles of temperature, age, velocity and shear deformation are presented. The geographic origin of the ice column at this position extends 320 km upstream and therefore does not leave the DML region. | ||||||
BibTeX:
@article{Calov1998AGla2,
author = {Calov, R. and Savvin, A. and Greve, R. and Hansen, I. and Hutter, K.},
title = {Simulation of the {Antarctic} ice sheet with a three-dimensional polythermal ice-sheet model, in support of the {EPICA} project.},
journal = {Annals of Glaciology},
year = {1998},
volume = {27},
pages = {201-206},
url = {http://www.ingentaconnect.com/content/igsoc/agl/2000/00000030/00000001/art00012}
}
|
||||||
| Carabajal, C. C. & Harding, D. J. | 2005 | ICESat validation of SRTM C-band digital elevation models | Geophysical Research Letters 32 , L22S01 | DEM | ; accuracy; | DOI URL |
| Abstract: The Geoscience Laser Altimeter System (GLAS) on the Ice, Cloud, and land Elevation Satellite (ICESat) provides a globally-distributed data set well suited for evaluating the vertical accuracy of Shuttle Radar Topography Mission (SRTM) digital elevation models (DEMs). The horizontal error (2.4 ± 7.3 m) and vertical error (0.04 ± 0.13 m per degree of incidence angle) for the ICESat data used are small compared to those for SRTM. Using GLAS echo waveforms we document differences between the SRTM C-band phase center and the highest, centroid, and lowest elevations within ICESat laser footprints in the western United States. In areas of low relief and sparse tree cover, the mean and standard deviation of elevation differences between the ICESat centroid and SRTM are 0.60 ± 3.46 m. The differences are 5.61 ± 15.68 m in high relief, sparse tree cover areas, and 3.53 ± 8.04 m in flat areas with dense tree cover. The largest differences occur in rugged, denselyvegetated regions. |
||||||
BibTeX:
@article{carabajal2005grs,
author = {Carabajal, C. C. and Harding, D. J.},
title = {{ICESat} validation of {SRTM C-band} digital elevation models},
journal = {Geophysical Research Letters},
year = {2005},
volume = {32},
pages = {L22S01},
url = {http://icesat.gsfc.nasa.gov/publications/GRL/carabajal-1.pdf},
doi = {doi:10.1029/2005GL023957}
}
|
||||||
| Carlisle, B. H. | 2000 | The highs and lows of DEM error - developing a spatially distributed DEM error model. | Proceedings of the 5th International Conference on GeoComputation. University of Greenwich, United Kingdom, 23-25 | uncertainty | Interpolation; Differential GPS; Digital Photogrammetry; Accuracy; Geomorphology | URL |
| Abstract: Despite the last decade's increasing concern for understanding and working with the uncertainty within DEMs, knowledge about DEM error is still at a primitive stage and incorporation of this knowledge into DEM-based modelling applications has only developed to a limited extent. This research addresses the limitations of using a single RMSE value to portray the uncertainty associated with a DEM by developing a technique for creating a spatially distributed DEM error model - an error surface. The technique is based on the hypothesis that the distribution and scale of errors within a DEM are at least partly related to characteristics of the terrain. The technique involves the collection of high accuracy elevation measurements to compute DEM error, the generation of a set of terrain parameters to characterise the terrain and developing regression models to define the relationship between DEM error and terrain character. The regression models form the basis for creating a RMSE surface to portray DEM error. These error surfaces provide more detailed information about DEM error than a single global estimate of RMSE and an initial assessment of these surfaces indicates they are of sufficient quality for use in stochastic simulations of the impact of DEM error on spatial modelling applications. Error surfaces also have the potential to open the door to a more deterministic approach towards incorporation of uncertainty into spatial modelling by means of probabilistic modelling techniques. | ||||||
BibTeX:
@inproceedings{Carlisle2000proc,
author = {Carlisle, Bruce H.},
title = {The highs and lows of {DEM} error - developing a spatially distributed {DEM} error model.},
booktitle = {Proceedings of the 5th International Conference on GeoComputation.},
year = {2000},
pages = {23-25},
url = {http://www.geocomputation.org/2000/gc999/gc999.htm}
}
|
||||||
| Cazorzi, F. & Fontana, G. D. | 1996 | Snowmelt modelling by combining air temperature and a distributed radiation index. [BibTeX] |
Journal of Hydrology 181 , 169-187 | TIM | DOI |
|
BibTeX:
@article{Cazorzi1996JHyd,
author = {Cazorzi, F. and Fontana, G. Dalla},
title = {Snowmelt modelling by combining air temperature and a distributed radiation index.},
journal = {Journal of Hydrology},
year = {1996},
volume = {181},
pages = {169-187},
doi = {10.1016/0022-1694(95)02913-3}
}
|
||||||
| Chaplot, V., Darboux, F., Bourennane, H., Leguédois, S., Silvera, N. & Phachomphon, K. | 2006 | Accuracy of interpolation techniques for the derivation of digital elevation models in relation to landform types and data density. | Geomorphology 77 , 126-141 | DEM | ; Interpolation method; Sampling density; Landform type; Spatial scale | DOI |
| Abstract: One of the most important scientific challenges of digital elevation modeling is the development of numerical representations of large areas with a high resolution. Although there have been many studies on the accuracy of interpolation techniques for the generation of digital elevation models (DEMs)next term in relation to landform types and data quantity or density, there is still a need to evaluate the performance of these techniques on natural landscapes of differing morphologies and over a large range of scales. To perform such an evaluation, we investigated a total of six sites, three in the mountainous region of northern Laos and three in the more gentle landscape of western France, with various surface areas from micro-plots, hillslopes, and catchments. The techniques used for the interpolation of point height data with density values from 4 to 109 points/km2 include: inverse distance weighting (IDW), ordinary kriging (OK), universal kriging (UK), multiquadratic radial basis function (MRBF), and regularized spline with tension (RST). The study sites exhibited coefficients of variation (CV) of altitude between 12% and 78%, and isotropic to anisotropic spatial structures with strengths from weak (with a nugget/sill ratio of 0.8) to strong (0.01). Irrespective of the spatial scales or the variability and spatial structure of altitude, few differences existed between the interpolation methods if the sampling density was high, although MRBF performed slightly better. However, at lower sampling densities, kriging yielded the best estimations for landscapes with strong spatial structure, low CV and low anisotropy, while RST yielded the best estimations for landscapes with low CV and weak spatial structure. Under conditions of high CV, strong spatial structure and strong anisotropy, IDW performed slightly better than the other method. The prediction errors in height estimation are discussed in relation to the possible interactions with spatial scale, landform types, and data density. These results indicate that the accuracy of interpolation techniques for previous termDEMnext term generation should be tested not only in relation to landform types and data density but also to their applicability to multi-scales. | ||||||
BibTeX:
@article{Chaplot2006GM,
author = {Chaplot, Vincent and Darboux, Fr{\'e}d{\'e}ric and Bourennane, Hocine and Legu{\'e}dois, Sophie and Silvera, Norbert and Phachomphon, Konngkeo},
title = {Accuracy of interpolation techniques for the derivation of digital elevation models in relation to landform types and data density.},
journal = {Geomorphology},
year = {2006},
volume = {77},
pages = {126-141},
doi = {10.1016/j.geomorph.2005.12.010}
}
|
||||||
| Charbit, S., Ritz, C., Philippon, G., Peyaud, V. & Kageyama, M. | 2007 | Numerical reconstructions of the Northern Hemisphere ice sheets through the last glacial-interglacial cycle. | Climate of the Past 3 , 15-37 | ISM | ||
| Abstract: A 3-dimensional thermo-mechanical ice-sheet model is used to simulate the evolution of the Northern Hemisphere ice sheets through the last glacial-interglacial cycle. The ice-sheet model is forced by the results from six different atmospheric general circulation models (AGCMs). The climate evolution over the period under study is reconstructed using two climate equilibrium simulations performed for the Last Glacial Maximum (LGM) and for the present-day periods and an interpolation through time between these snapshots using a glacial index calibrated against the GRIP delta^18O record. Since it is driven by the timing of the GRIP signal, the temporal evolution of the ice volume and the ice-covered area is approximately the same from one simulation to the other. However, both ice volume curves and spatial distributions of the ice sheets present some major differences from one AGCM forcing to the other. The origin of these differences, which are most visible in the maximum amplitude of the ice volume, is analyzed in terms of differences in climate forcing. This analysis allows for a partial evaluation of the ability of GCMs to simulate climates consistent with the reconstructions of past ice sheets. Although some models properly reproduce the advance or retreat of ice sheets in some specific areas, none of them is able to reproduce both North American or Eurasian ice complexes in full agreement with observed sea-level variations and geological data. These deviations can be attributed to shortcomings in the climate forcing and in the LGM ice-sheet reconstruction used as a boundary condition for GCM runs, but also to missing processes in the ice-sheet model itself. | ||||||
BibTeX:
@article{Charbit2007CP,
author = {Charbit, Sylvie and Ritz, Catherine and Philippon, G. and Peyaud, V. and Kageyama, M.},
title = {Numerical reconstructions of the {Northern Hemisphere} ice sheets through the last glacial-interglacial cycle.},
journal = {Climate of the Past},
year = {2007},
volume = {3},
pages = {15-37}
}
|
||||||
| Charbit, S., Ritz, C. & Ramstein, G. | 2002 | Simulations of Northern Hemisphere ice-sheet retreat: sensitivity to physical mechanisms involved during the Last Deglaciation. | Quaternary Science Reviews 21 , 243-265 | ISM | sensitivity; ice sheet model; AGCM; climate interpolation; coupling; ISM; LGM; | DOI |
| Abstract: A 3-dimensional thermomechanical ice-sheet model is used to simulate the evolution of the geometry of Northern Hemisphere ice sheets through the Last Deglaciation. The ice-sheet model is forced by a time-evolving climatology provided by the linear interpolation through time of climate snapshots simulated by the LMD5.3 atmospheric general circulation model (AGCM) at different periods of the Last Deglaciation (21, 15, 9, 6 and 0 kyr BP). The AGCM is driven by insolation, atmospheric CO2 content, ice-sheet configuration and sea surface temperatures. Although our approach is able to produce the complete continental ice retreat, our simulated deglaciation presents a phase-lag with reconstructions based on observational evidences. This suggests that physical mechanisms related to climate forcing and/or ice-sheet internal dynamics are not properly represented. The influence of millennialscale forcing, feedback mechanisms between ice-sheet elevation and surface mass balance and parameterization of the ice flow is also tested through a set of sensitivity experiments. The rapid variability has a strong impact on the evolution of the ice volume because of nonlinear effects in temperature-mass balance relationships. Fennoscandia appears to be strongly sensitive to the small-scale ice-sheet instability. Both ice sheets are to some extent sensitive to an increased basal sliding. | ||||||
BibTeX:
@article{charbit2002qsr,
author = {Charbit, Sylvie and Ritz, Catherine and Ramstein, Gilles},
title = {Simulations of {Northern Hemisphere} ice-sheet retreat: sensitivity to physical mechanisms involved during the Last Deglaciation.},
journal = {Quaternary Science Reviews},
year = {2002},
volume = {21},
pages = {243-265},
doi = {10.1016/S0277-3791(01)00093-2}
}
|
||||||
| Christensen, O. B., Christensen, J. H., Machenhauer, B. & Botzet, M. | 1998 | Very High-Resolution Regional Climate Simulations over Scandinavia - Present Climate. | Journal of Climate 11 , 3204-3229 | Climate | URL |
|
| Abstract: The hydrological cycle on a regional scale is poorly represented with a present-day coarse resolution general circulation model (GCM). With a dynamical downscaling technique, in which a regional higher-resolution climate model (RCM) is nested into the GCM, this starts to become feasible. Here the authors go one step further with a double nesting approach, applying an RCM at 19-km horizontal resolution nested into an RCM at 57-km resolution over an area covering the Scandinavian Peninsula. A 9-yr-long time-slice simulation is performed with the driving boundary conditions taken from a fully coupled ocean–atmosphere GCM experiment, the recently completed ECHAM4/OPYC3 control simulation performed by the Max Planck Institute for Meteorology in Hamburg. With increasing resolution, local effects playing a significant role in the hydrological budget become better and better resolved and are more realistically simulated. It is found in particular that in mountainous regions the high-resolution simulation shows improvements in the simulation of hydrologically relevant fields such as runoff and snow cover. Also, the distribution of precipitation on different intensity classes is most realistically simulated in the high-resolution simulation. It does, however, inherit certain large-scale systematic errors from the driving GCM. In many cases these errors increase with increasing resolution. Model verification of near-surface temperature and precipitation is made using a new gridded climatology based on a high-density station network for the Scandinavian countries compiled for the present study. The simulated runoff is compared with observed data from Sweden extracted from a Swedish climatological atlas. These runoff data indicate that the precipitation analyses are underestimating the true precipitation by as much as 96% on an annual basis in the most mountainous region of Sweden. This fact as well as estimates of the underestimation in other areas of Scandinavia make the high-resolution RCM simulations appear more realistic. | ||||||
BibTeX:
@article{Christensen1998CC,
author = {Christensen, Ole B. and Christensen, Jens H. and Machenhauer, Bennert and Botzet, Michael},
title = {Very High-Resolution Regional Climate Simulations over {Scandinavia} - Present Climate.},
journal = {Journal of Climate},
year = {1998},
volume = {11},
pages = {3204-3229},
url = {http://ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175%2F1520-0442%281998%29011%3C3204%3AVHRRCS%3E2.0.CO%3B2}
}
|
||||||
| Clarke, G. K. | 2000 | Basics of ice sheet modelling. [BibTeX] |
Unpublished notes | ISM | ISM; glaciology; | |
BibTeX:
@unpublished{clarke2000notes1,
author = {Clarke, Garry K.C.},
title = {Basics of ice sheet modelling.},
journal = {Unpublished notes},
year = {2000}
}
|
||||||
| Clarke, G. K. | 2000 | Notes on numerical solution of differential equations. Geophysics 516. [BibTeX] |
Unpublished notes | ISM | ISM; | |
BibTeX:
@unpublished{clarke2000notes2,
author = {Clarke, Garry K.C.},
title = {Notes on numerical solution of differential equations. Geophysics 516.},
journal = {Unpublished notes},
year = {2000}
}
|
||||||
| Clarke, G. K., Nitsan, U. & Paterson, W. | 1977 | Strain heating and creep instability in glaciers and ice sheets. [BibTeX] |
Reviews of Geophysics and Space Physics 15 , 235-247 | ISM | ISM; modelling; glaciology; | |
BibTeX:
@article{clarke1977rgsp,
author = {Clarke, Garry K.C. and Nitsan, U. and Paterson, W.S.B.},
title = {Strain heating and creep instability in glaciers and ice sheets.},
journal = {Reviews of Geophysics and Space Physics},
year = {1977},
volume = {15},
pages = {235-247}
}
|
||||||
| Cliffe, K. & Morland, L. | 2002 | Full and reduced model solutions of steady axi-symmetric ice sheet flow over bed topography with moderate slopes. | Continuum Mechanics and Thermodynamics 14 , 149-164 | ISM | shallow ice approximation, thermo mechanical coupling; ISM; | |
| Abstract: Solutions of steady axi-symmetric ice-sheet flows over beds with moderate slope topography are obtained by finite element calculations on the full equations for the free-surface problem, and by numerical solutions of two-point boundary-value problems arising from the Enhanced Reduced Model. The standard Reduced Model is strictly valid only for bed slopes not exceeding the very small surface slope of the ice sheet, whereas the Enhanced Reduced Model is a leading order approximation for larger moderate bed slopes, with a correction error depending on both the bed slope and the length scale or amplitude of the topography variation. The solution comparisons demonstrate the consistency between the finite-element solutions of the full equations and the Enhanced Reduced Model solutions for moderate bed slopes, with differences within the predicted correction errors, which confirms the validity and accuracy of both the Enhanced Reduced Model solution and the finite element algorithm for the full free-surface problem, and further, demonstrate the merits of the much simpler Enhanced Reduced Model as a leading order approximation. | ||||||
BibTeX:
@article{cliffe2002cmechterm,
author = {Cliffe, K.A. and Morland, L.W.},
title = {Full and reduced model solutions of steady axi-symmetric ice sheet flow over bed topography with moderate slopes.},
journal = {Continuum Mechanics and Thermodynamics},
year = {2002},
volume = {14},
pages = {149-164}
}
|
||||||
| Cliffe, K. & Morland, L. | 2001 | A thermo-mechanically coupled test case for axi-symmetric ice sheet flow. | Continuum Mechanics and Thermodynamics 13 , 135-148 | ISM | shallow ice approximation, thermo mechanical coupling; ISM; | |
| Abstract: This paper presents a set of approximate, but highly accurate, numerical solutions to the equations governing the flow of an axi-symmetric ice sheet with thermo-mechanical coupling within the ice sheet. The solution is obtained by using a finite-element method. The accuracy of the method is verified by means of a careful comparison of the results obtained with the finite-element method and those obtained using a thin ice approximation to reduce the problem to a set of ordinary differential equations. Two of the sources for the differences between the finite-element solution and the reduced solution, namely the discretisation error and the error introduced by the thin ice approximation are investigated. The magnitudes of both these differences are estimated by solving a sequence of problems on a range of computational grids. Excellent agreement between the two sets of results is achieved. Results from a simple direct computation by the finite-element method are also presented. | ||||||
BibTeX:
@article{cliffe2001cmechterm,
author = {Cliffe, K.A. and Morland, L.W.},
title = {A thermo-mechanically coupled test case for axi-symmetric ice sheet flow.},
journal = {Continuum Mechanics and Thermodynamics},
year = {2001},
volume = {13},
pages = {135-148}
}
|
||||||
| Cliffe, K. & Morland, L. | 2000 | Full and reduced model solutions of steady axi-symmetric ice sheet flow over small and large bed topography slopes. | Continuum Mechanics and Thermodynamics 12 (3) , 195-216 | ISM | shallow ice approximation; ISM; topography; | |
| Abstract: Two numerical methods for solving the full steady ice-sheet equations in axi-symmetric flow are described. The free-boundary problem is treated by transforming the problem to a fixed domain using either an orthogonal co-ordinate transformation or a variant of a transformation proposed by Landau, and difficulties with the former, more sophisticated, method are demonstrated. The simpler Reduced Model is also presented, and accurate solutions for flows over bed topography with moderate to large slopes are generated by an inverse method for comparison with the numerical solutions of the full equations. The reduced model is not valid for such bed slopes, and the comparisons demonstrate the extent and nature of the errors arising from the use of the simpler model. | ||||||
BibTeX:
@article{cliffe2000cmechterm,
author = {Cliffe, K.A. and Morland, L.W.},
title = {Full and reduced model solutions of steady axi-symmetric ice sheet flow over small and large bed topography slopes.},
journal = {Continuum Mechanics and Thermodynamics},
year = {2000},
volume = {12},
number = {3},
pages = {195-216}
}
|
||||||
| Codilean, A. T., Bishop, P. & Hoey, T. B. | 2006 | Surface process models and the links between tectonics and topography. | Progress in Physical Geography 30 (3) , 307-333 | topography; modelling; SPM; geomorphology; | DOI |
|
| Abstract: Advances in the theoretical understanding of large-scale tectonic and surface processes, along with a rapid growth of computing technology, have stimulated interest in the use of numerical surface process models (SPMs) of long-term landscape evolution, especially in relation to the links between tectonics and topography. Because of these advances and possibilities and because SPMs continue to play an important part in recent geological, geomorphological, thermochronological and other geosciences research, the models warrant review and assessment. This review summarizes and evaluates the important issues concerning SPMs of long-term landscape evolution that have been addressed only in a passing way by previous authors. The issues reviewed here are: (1) the formulation of the 'laws' that represent fluvial and hillslope processes in SPMs; (2) the implementation of the various algorithms on numerical grids; (3) model parameterization and calibration; and (4) model testing. | ||||||
BibTeX:
@article{Codilean2006PPG,
author = {Codilean, Alexandru T. and Bishop, Paul and Hoey, Trevor B.},
title = {Surface process models and the links between tectonics and topography.},
journal = {Progress in Physical Geography},
year = {2006},
volume = {30},
number = {3},
pages = {307-333},
doi = {10.1191/0309133306pp480ra}
}
|
||||||
| Collins, W. D., Bitz, C. M., Blackmon, M. L., Bonan, G. B., Bretherton, C. S., Carton, J. A., Chang, P., Doney, S. C., Hack, J. J., Henderson, T. B., Kiehl, J. T., Large, W. G., McKenna, D. S., Santer, B. D. & Smith, R. D. | 2006 | The Community Climate System Model Version 3 (CCSM3). | Journal of Climate 19 (11) , 2122-2143 | DOI |
||
| Abstract: The Community Climate System Model version 3 (CCSM3) has recently been developed and released to the climate community. CCSM3 is a coupled climate model with components representing the atmosphere, ocean, sea ice, and land surface connected by a flux coupler. CCSM3 is designed to produce realistic simulations over a wide range of spatial resolutions, enabling inexpensive simulations lasting several millennia or detailed studies of continental-scale dynamics, variability, and climate change. This paper will show results from the configuration used for climate-change simulations with a T85 grid for the atmosphere and land and a grid with approximately 1° resolution for the ocean and sea ice. The new system incorporates several significant improvements in the physical parameterizations. The enhancements in the model physics are designed to reduce or eliminate several systematic biases in the mean climate produced by previous editions of CCSM. These include new treatments of cloud processes, aerosol radiative forcing, land–atmosphere fluxes, ocean mixed layer processes, and sea ice dynamics. There are significant improvements in the sea ice thickness, polar radiation budgets, tropical sea surface temperatures, and cloud radiative effects. CCSM3 can produce stable climate simulations of millennial duration without ad hoc adjustments to the fluxes exchanged among the component models. Nonetheless, there are still systematic biases in the ocean–atmosphere fluxes in coastal regions west of continents, the spectrum of ENSO variability, the spatial distribution of precipitation in the tropical oceans, and continental precipitation and surface air temperatures. Work is under way to extend CCSM to a more accurate and comprehensive model of the earth's climate system. | ||||||
BibTeX:
@article{Collins2006JC,
author = {Collins, William D. and Bitz, Cecilia M. and Blackmon, Maurice L. and Bonan, Gordon B. and Bretherton, Christopher S. and Carton, James A. and Chang, Ping and Doney, Scott C. and Hack, James J. and Henderson, Thomas B. and Kiehl, Jeffrey T. and Large, William G. and McKenna, Daniel S. and Santer, Benjamin D. and Smith, Richard D.},
title = {The Community Climate System Model Version 3 {(CCSM3)}.},
journal = {Journal of Climate},
year = {2006},
volume = {19},
number = {11},
pages = {2122-2143},
doi = {10.1175/JCLI3761.1}
}
|
||||||
| Comber, A. J., Fisher, P. F., Harvey, F., Gahegan, M. & Wadsworth, R. | 2006 | Using Metadata to Link Uncertainty and Data Quality Assessments. [BibTeX] |
Progress in Spatial Data Handling. 12th International Symposium on Spatial Data Handling. Springer, Berlin , 279-292 | DOI |
||
BibTeX:
@inproceedings{Comber2006SDH,
author = {Comber, Alexis J. and Fisher, Peter F. and Harvey, F. and Gahegan, M. and Wadsworth, Richard},
title = {Using Metadata to Link Uncertainty and Data Quality Assessments.},
booktitle = {Progress in Spatial Data Handling. 12th International Symposium on Spatial Data Handling.},
publisher = {Springer, Berlin},
year = {2006},
volume = {6},
pages = {279-292},
doi = {10.1007/3-540-35589-8_18}
}
|
||||||
| Comber, A. J., Fisher, P. F. & Wadsworth, R. | 2004 | Integrating land-cover data with different ontologies: identifying change from inconsistency. | International Journal of Geographical Information Science 18 (7) , 691-708 | uncertainty | DEM; uncertainty; | DOI |
| Abstract: Spatially coincident land-cover information frequently varies due to technological and political variations. This is especially problematic for timeseries analyses. We present an approach using expert expressions of how the semantics of different datasets relate to integrating temporal time series landcover information where the classification classes have fundamentally changed. We use land-cover mapping in the UK (LCMGB and LCM2000) as example data sets because of the extensive object-based meta-data in the LCM2000. Inconsistencies between the two datasets can arise from random, gross and systematic error and from an actual change in land cover. Locales of possible land-cover change are inferred by comparing characterizations derived from the semantic relations and meta-data. Field visits showed errors of omission to be 21% and errors of commission to be 28%, despite the accuracy limitations of the land-cover information when compared with the field survey component of the Countryside Survey 2000. | ||||||
BibTeX:
@article{comber2004ijgis,
author = {Comber, Alexis J. and Fisher, Peter F. and Wadsworth, Richard},
title = {Integrating land-cover data with different ontologies: identifying change from inconsistency.},
journal = {International Journal of Geographical Information Science},
year = {2004},
volume = {18},
number = {7},
pages = {691-708},
doi = {10.1080/13658810410001705316}
}
|
||||||
| Corripio, J. G. | 2003 | Vectorial algebra algorithms for calculating terrain parameters from DEMs and solar radiation modelling in mountainous terrain | Taylor & Francis International Journal of Geographical Information Science 17 (1) , 1-23 | DEM | DOI |
|
| Abstract: Terrain parameters derived from digital elevation models (DEMs), such as slope gradient, aspect and cell surface area, are represented as a vector normal to the surface and calculated using the minimum areal unit of the DEM, that is enclosed between four data points. The position of the Sun is calculated by applying rotational matrices to a unit vector defined at noon as a function of latitude and declination. The direct component of insolation intercepted by the cell surface is then calculated as a dot product between the unit vector in the direction of the Sun and the unit vector normal to surface, multiplied by direct normal irradiation. Hillshading is computed by scanning the projection of cells onto a solar illumination plane perpendicular to the Sun direction. Horizon angles and estimated sky view factor are calculated using a more economical algorithm than a rigorous evaluation of all the angles subtended by every grid cell to each other. The performance of the slope algorithm is evaluated using a synthetic surface and real world examples are given for the Mont Blanc Massif, in the French Alps. |
||||||
BibTeX:
@article{Corripio2003IJGIS,
author = {Corripio, Javier G.},
title = {{Vectorial algebra algorithms for calculating terrain parameters from DEMs and solar radiation modelling in mountainous terrain}},
journal = {International Journal of Geographical Information Science},
publisher = {Taylor \& Francis},
year = {2003},
volume = {17},
number = {1},
pages = {1-23},
doi = {10.1080/713811744}
}
|
||||||
| Couclelis, H. | 2003 | The Certainty of Uncertainty: GIS and the Limits of Geographic Knowledge. | Transactions in GIS 7 (2) , 165-175 | DOI |
||
| Abstract: Considerable effort has been devoted over the years to fighting uncertainty in geographic information in its different manifestations. Thus far, research on handling inaccuracy, fuzziness, error and related issues has focused for the most part on problems with spatial data and their direct products, typically representations of spatial objects or fields. This paper seeks to broaden the discussion of uncertainty in the geospatial domain by shifting the focus from information to knowledge. It turns out that there is a surprising number of things that we cannot know (or questions we cannot answer) that are not the result of imperfect information. Forms of not knowing are pervasive in domains as diverse as mathematics, logic, physics, and linguistics, and are apparently irreducible. This being the case it may help to explore how these realms of ignorance may affect our efforts. The paper distinguishes three different modes or forms of geospatial knowledge production, and argues that each of them has built–in imperfections, for reasons of logical principle and not just empirical fact. While much can and needs to be done to manage and resolve uncertainties where possible, I argue for accepting that uncertainty is an intrinsic property of complex knowledge and not just a flaw that needs to be excised. | ||||||
BibTeX:
@article{Couclelis2003TIGIS,
author = {Couclelis, Helen},
title = {The Certainty of Uncertainty: {GIS} and the Limits of Geographic Knowledge.},
journal = {Transactions in GIS},
year = {2003},
volume = {7},
number = {2},
pages = {165-175},
doi = {10.1111/1467-9671.00138}
}
|
||||||
| Couclelis, H. | 1996 | Towards an operational typology of geographic entities with ill-defined boundaries. [BibTeX] |
Geographic Objects with Indeterminate Boundaries. Taylor & Francis, London , 45-55 | GIS, uncertainty | ||
BibTeX:
@incollection{Couclelis1996inbook,
author = {Couclelis, Helen},
title = {Towards an operational typology of geographic entities with ill-defined boundaries.},
booktitle = {Geographic Objects with Indeterminate Boundaries.},
publisher = {Taylor \& Francis, London},
year = {1996},
pages = {45-55}
}
|
||||||
| CRU | 2006 | Climatic Research Unit, School of Environmental Sciences, University of East Anglia: 5x5 degree gridded temperature and precipitation data. [BibTeX] |
Data | School of Environmental Sciences University of East Anglia Norwich NR4 7TJ, UK |
||
BibTeX:
@misc{CRU2007,
author = {{CRU}},
title = {{Climatic Research Unit, School of Environmental Sciences, University of East Anglia: 5x5 degree gridded temperature and precipitation data.}},
year = {2006}
}
|
||||||
| Dahl-Jensen, D., Mosegaard, K., Gundestrup, N., Clow, G. D., Johnsen, S., Hansen, A. W. & Balling, N. | 1998 | Past temperatures directly from the Greenland ice sheet. | Science 282 (5387) , 268-271 | ISM | DOI |
|
| Abstract: A Monte Carlo inverse method has been used on the temperature profiles measured down through the Greenland Ice Core Project (GRIP) borehole, at the summit of the Greenland Ice Sheet, and the Dye 3 borehole 865 kilometers farther south. The result is a 50,000-year-long temperature history at GRIP and a 7000-year history at Dye 3. The Last Glacial Maximum, the Climatic Optimum, the Medieval Warmth, the Little Ice Age, and a warm period at 1930 A.D. are resolved from the GRIP reconstruction with the amplitudes -23 kelvin, +2.5 kelvin, +1 kelvin, -1 kelvin, and +0.5 kelvin, respectively. The Dye 3 temperature is similar to the GRIP history but has an amplitude 1.5 times larger, indicating higher climatic variability there. The calculated terrestrial heat flow density from the GRIP inversion is 51.3 milliwatts per square meter. | ||||||
BibTeX:
@article{Dahl-Jensen1998Science,
author = {Dahl-Jensen, D. and Mosegaard, K. and Gundestrup, N. and Clow, G. D. and Johnsen, S.J. and Hansen, A. W. and Balling, N.},
title = {Past temperatures directly from the {Greenland} ice sheet.},
journal = {Science},
year = {1998},
volume = {282},
number = {5387},
pages = {268-271},
doi = {10.1126/science.282.5387.268}
}
|
||||||
| Davis, T. J. & Keller, C. P. | 1997 | Modelling and visualizing multiple spatial uncertainties. | Computers & Geoscience 23 (4) , 397-408 | uncertainty | GIS; visualisation; uncertainty; fuzzy; vector; slope stability model; modelling; | URL |
| Abstract: This paper presents the results of research into the modelling and visualization of multiple types of uncertainty - each exhibiting distinct spatial characteristics. Slope stability modelling is utilized as a vehicle to bring together uncertainties in categorical spatial data and continuous spatial data. A variety of static visualization methods are discussed, as well as the implications of using an interactive animated display to explore multiple realizations of a continuous surface. The results indicate that careful definitions of allowable uncertainty, and the implications thereof, are required to calibrate an interactive animation that will be utilized by non-specialists. It is argued that this holds particularly true in the situation of risk management decisions. | ||||||
BibTeX:
@article{davis1997cg,
author = {Davis, Trevor J. and Keller, C. Peter},
title = {Modelling and visualizing multiple spatial uncertainties.},
journal = {Computers \& Geoscience},
year = {1997},
volume = {23},
number = {4},
pages = {397-408},
url = {http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6V7D-3T7J19D-K-1&_cdi=5840&_user=946230&_orig=browse&_coverDate=05%2F31%2F1997&_sk=999769995&view=c&wchp=dGLbVtz-zSkWA&md5=352eda0c0fb094e72be63ef57ff0b9ea&ie=/sdarticle.pdf}
}
|
||||||
| Davis, T. J. & Keller, C. P. | 1997 | Modelling uncertainty in natural resource analysis using fuzzy sets and Monte Carlo simulation: slope stability prediction. | International Journal of Geographical Information Science 11 (5) , 409-434 | uncertainty | Uncertainty; DEM ; error model; MCS; fuzzy sets; | DOI |
| Abstract: The techniques of fuzzy logic and Monte Carlo simulation are combined to address two incompatible types of uncertainty present in most natural resource data: thematic classification uncertainty and variance in unclassified continuously distributed data. The resultant model of uncertainty is applied to an infinite slope stability model using data from Louise Island, British Columbia. Results are summarized so as to answer forestry decision support queries. The proposed model of uncertainty in resource data analysis is found to have utility in combining different types of uncertainty, and efficiently utilizing available metadata. Integration of uncertainty data models with visualization tools is considered a necessary prerequisite to effective implementation in decision support systems. | ||||||
BibTeX:
@article{Davis1997IJGIS,
author = {Davis, Trevor J. and Keller, C. Peter},
title = {Modelling uncertainty in natural resource analysis using fuzzy sets and {Monte Carlo} simulation: slope stability prediction.},
journal = {International Journal of Geographical Information Science},
year = {1997},
volume = {11},
number = {5},
pages = {409-434},
doi = {10.1080/136588197242239}
}
|
||||||
| Debreu, L. & Blayo, E. | 2002 | AGRIF: Adaptive Grid Refinement In Fortran. [BibTeX] |
Technical Report (0262) Institut National de Recherche en Informatique et en Automatique | Subgrid | URL |
|
BibTeX:
@techreport{Debreu2002tech,
author = {Debreu, Laurent and Blayo, Eric},
title = {{AGRIF}: Adaptive Grid Refinement In Fortran.},
year = {2002},
number = {0262},
url = {http://hal.inria.fr/docs/00/06/99/12/PDF/RT-0262.pdf}
}
|
||||||
| DeConto, R. M. & Pollard, D. | 2003 | A coupled climate-ice sheet modeling approach to the Early Cenozoic history of the Antarctic ice sheet. | Palaeogeography, Palaeclimatology, Palaeoecology 198 , 39-52 | ISM | Antarctica; Ice sheets; Oligocene; Paleoclimate; Drake Passage; ice sheet model; coupled model; climate model; ISM; | |
| Abstract: The sudden, widespread glaciation of Antarctica and the associated shift toward colder temperatures near the Eocene-Oligocene boundary (~34 Ma) represents one of the most fundamental reorganizations of the global climate system recognized in the geologic record. This glacial inception and the subsequent evolution of the early East Antarctic Ice Sheet (EAIS) are simulated using a new, coupled global climate-dynamical ice sheet model accounting for the paleogeography, greenhouse gas concentrations, changing orbital parameters, and varying ocean heat transport. Suites of long (105 yr) climate-ice sheet simulations are used to investigate the effects of declining atmospheric CO2, compared to those of the tectonic opening of Southern Ocean gateways and the timing of mountain uplift in the Antarctic interior. In contrast to the established paradigm for the glaciation of Antarctica, which centers on the opening of the Southern Ocean gateways and the thermal isolation of the continent, our results show that declining Cenozoic pCO2 may have played the dominant role. First, small isolated ice caps formed on the highest Antarctic plateaus. Then, as a CO2 threshold between ~3x and 2x pre-industrial level (PAL) was crossed, height^ mass balance feedbacks were initiated during orbital periods with cold austral summers, triggering much larger, highly dynamic terrestrial ice sheets. As CO2 continued to decline, these isolated ice caps eventually merged into a permanent continental-scale EAIS. In our model, neither the opening of the Southern Ocean gateways nor mountain uplift significantly affected the timing of the major ice sheet transition, given a scenario of gradually declining CO2 from 4x to 2x PAL over 10 million years around the Eocene-Oligocene boundary. | ||||||
BibTeX:
@article{deconto2003ppp,
author = {DeConto, Robert M. and Pollard, David},
title = {A coupled climate-ice sheet modeling approach to the {Early Cenozoic} history of the {Antarctic} ice sheet.},
journal = {Palaeogeography, Palaeclimatology, Palaeoecology},
year = {2003},
volume = {198},
pages = {39-52}
}
|
||||||
| Deutsch, C. V. & Cockerham, P. W. | 1994 | Practical considerations in the application of simulated annealing to stochastic simulation. | Mathematical Geology 26 (1) , 67-82 | DOI |
||
| Abstract: Realizations generated by conditional simulation techniques must honor as much data as possible to be reliable numerical models of the attribute under study. The application of optimization methods such as simulated annealing to stochastic simulation has the potential to honor more data than conventional geostatistical simulation techniques. The essential feature of this approach is the formulation of stochastic imaging as an optimization problem with some specified objective function. The data to be honored by the stochastic images are coded as components in a global objective function. This paper describes the basic algorithm and then addresses a number of practical questions: (1) what are the criteria for adding a component to the global objective function? (2) what perturbation mechanism should be employed in the annealing simulation? (3) when should the temperature be lowered in the annealing procedure? (4) how are edge/border nodes handled? (5) how are local conditioning data handled? and (6) how are multiple components weighted in the global objective function? | ||||||
BibTeX:
@article{Deutsch1994MG,
author = {Deutsch, Clayton V. and Cockerham, Perry W.},
title = {Practical considerations in the application of simulated annealing to stochastic simulation.},
journal = {Mathematical Geology},
year = {1994},
volume = {26},
number = {1},
pages = {67-82},
doi = {10.1007/BF02065876}
}
|
||||||
| Devillers, R., Bédard, Y. & Jeansoulin, R. | 2005 | Multidimensional Management of Geospatial Data Quality Information for its Dynamic Use Within GIS. | Photogrammetric Engineering and Remote Sensing 71 (2) , 205-215 | |||
| Abstract: Metadata should help users to assess the quality (fitness for use) of geospatial data, thus reducing the risk of data misuse. However, metadata presents limitations and remain largely unused. There still exists a need to provide information to users about data quality in a more meaningful way. This research aims to dynamically communicate quality information to the users in a rapid and intuitive way in order to reduce user meta-uncertainty related to geospatial data quality, and then reduce the risks of data misuses. Such a solution requires a data model able to support heterogeneous data quality information at different levels of analysis. Using a multidimensional database approach, this paper proposes a conceptual framework named the Quality Information Management Model (QIMM) relying on quality dimensions and measures. This allows a user to easily and rapidly navigate into the quality information using a Spatial On-Line Analytical Processing (SOLAP) client-tied to its GIS application. QIMM potential is illustrated by examples, and then a prototype and ways to communicate data quality to users are explored. |
||||||
BibTeX:
@article{Devillers2005PERS,
author = {Devillers, Rodolphe and B\'edard, Yvan and Jeansoulin, Robert},
title = {Multidimensional Management of Geospatial Data Quality Information for its Dynamic Use Within {GIS}.},
journal = {Photogrammetric Engineering and Remote Sensing},
year = {2005},
volume = {71},
number = {2},
pages = {205-215}
}
|
||||||
| Dikau, R. | 1996 | Geomorphologische Reliefklassifikation und -analyse. [BibTeX] |
Beiträge zur Physiogeographie: Festschrift für Dietrich Barsch. Geogr. Inst. Univ. Heidelberg | DEM | geomorphology; terrain analysis; feature extraction; | |
BibTeX:
@incollection{dikau1996hga,
author = {Dikau, Richard},
title = {Geomorphologische Reliefklassifikation und -analyse.},
booktitle = {Beitr\"age zur Physiogeographie: Festschrift f\"ur Dietrich Barsch.},
publisher = {Geogr. Inst. Univ. Heidelberg},
year = {1996},
volume = {104}
}
|
||||||
| Drewry, D. | 1983 | Antarctic glaciological and geophysical folio. [BibTeX] |
Scott Polar Research Institute | ISM | data; antarctica; glaciology; | |
BibTeX:
@manual{drewry1983folio,
author = {Drewry, D.J.},
title = {Antarctic glaciological and geophysical folio.},
year = {1983}
}
|
||||||
| Drogue, G., Humbert, J., Deraisme, J., Mahr, N. & Freslon, N. | 2002 | A statistical-topographic model using an omnidirectional parameterization of the relief for mapping orographic rainfall | International Journal of Climatology 22 (5) , 599-613 | DEM | France; multiple regression; geostatistics; digital elevation model; orographic effect; rainfall; DEM ; parameterization; | URL |
| Abstract: The knowledge of rainfall patterns is a key issue for regionalization in hydroclimatic studies. In mountainous areas, the sparsity of the measurement network and the complexity of relationships between rainfall and topography make an accurate and reliable spatialization of rainfall amounts at the regional scale difficult. The purpose of this paper is to present an objective, analytical and automatic model of quantification and mapping of orographic rainfall applied to the north-eastern part of France but also applicable in other complex terrain. PLUVIA distributes point measurements of monthly, annual and climatological rainfall to regularly spaced grid cells through a multiple regression analysis of rainfall versus morpho-topographic parameters derived from a digital elevation model. The use of an omnidirectional parameterization of the topography induced by a windowing technique allows better account to be taken of the synopticscale weather systems generating the different rainfall quantities of interest and the spatial scale of orographic effects. It also provides a more physical interpretation of geographical and topographical parameters selected for spatial estimation. The application relies on a network of more than 150 rain gauges spread over 30 000 km2 and concerns monthly to several yearly amounts of a sequence of 20 years. Advantages and limitations of the PLUVIA system are compared with those of two commonly used methods of multi-variate geostatistics: kriging with external drift and extended collocated co-kriging. | ||||||
BibTeX:
@article{drogue2002ijc,
author = {Drogue, G. and Humbert, J. and Deraisme, J. and Mahr, N. and Freslon, N.},
title = {A statistical-topographic model using an omnidirectional parameterization of the relief for mapping orographic rainfall},
journal = {International Journal of Climatology},
year = {2002},
volume = {22},
number = {5},
pages = {599-613},
url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/93515739/PDFSTART}
}
|
||||||
| Duckham, M., Mason, K., Stell, J. & Worboys, M. | 2001 | A formal approach to imperfection in geographic information. | Computers, Environment and Urban Systems 25 (1) , 89-103 | GIS | DOI |
|
| Abstract: Traditional computational models of geographic phenomena offer no room for imperfection. Underlying this tradition is the simplifying assumption that reality is certain, crisp, unambiguous, independent of context, and capable of quantitative representation. This paper reports on initial work which explicitly recognises that most geographic information is intrinsically imperfect. Based on an ontology of imperfection the paper explores a formal model of imperfect geographic information using multi-valued logic. The development of Java software able to assist with a geodemographic retail site assessment application is used to illustrate the utility of a formal approach. | ||||||
BibTeX:
@article{Duckham2001CEUS,
author = {Duckham, M. and Mason, K. and Stell, J. and Worboys, M.},
title = {A formal approach to imperfection in geographic information.},
journal = {Computers, Environment and Urban Systems },
year = {2001},
volume = {25},
number = {1},
pages = {89-103},
doi = {10.1016/S0198-9715(00)00040-5}
}
|
||||||
| Ehlschlaeger, C. R. | 2002 | Representing multiple spatial statistics in generalized elevation uncertainty models: moving beyond the variogram. | International Journal of Geographical Information Science 16 (3) , 259 - 285 | DEM | DEM; stochastic modelling; uncertainty; error; | URL |
| Abstract: Spatial data uncertainty models (SDUM) are necessary tools that quantify the reliability of results from geographical information system (GIS) applications. One technique used by SDUM is Monte Carlo simulation, a technique that quantifies spatial data and application uncertainty by determining the possible range of application results. A complete Monte Carlo SDUM for generalized continuous surfaces typically has three components: an error magnitude model, a spatial statistical model defining error shapes, and a heuristic that creates multiple realizations of error fields added to the generalized elevation map. This paper introduces a spatial statistical model that represents multiple statistics simultaneously and weighted against each other. This paper's case study builds a SDUM for a digital elevation model (DEM). The case study accounts for relevant shape patterns in elevation errors by reintroducing specific topological shapes, such as ridges and valleys, in appropriate localized positions. The spatial statistical model also minimizes topological artefacts, such as cells without outward drainage and inappropriate gradient distributions, which are frequent problems with random field-based SDUM. Multiple weighted spatial statistics enable two conflicting SDUM philosophies to co-exist. The two philosophies are 'errors are only measured from higher quality data' and 'SDUM need to model reality'. This article uses an automatic parameter fitting random field model to initialize Monte Carlo input realizations followed by an inter-map cell-swapping heuristic to adjust the realizations to fit multiple spatial statistics. The inter-map cell-swapping heuristic allows spatial data uncertainty modelers to choose the appropriate probability model and weighted multiple spatial statistics which best represent errors caused by map generalization. This article also presents a lag-based measure to better represent gradient within a SDUM. This article covers the inter-map cell-swapping heuristic as well as both probability and spatial statistical models in detail. | ||||||
BibTeX:
@article{ehlschlaeger2002ijgis,
author = {Ehlschlaeger, Charles Robert},
title = {Representing multiple spatial statistics in generalized elevation uncertainty models: moving beyond the variogram. },
journal = {International Journal of Geographical Information Science},
year = {2002},
volume = {16 },
number = {3},
pages = {259 - 285},
url = {http://journalsonline.tandf.co.uk/media/2gkjtjuqmnw6bewumma1/contributions/v/5/8/7/v587v93kvd1px8a8.pdf}
}
|
||||||
| Ehlschlaeger, C. R. | 1998 | The Stochastic Simulation Approach: Tools for Representing Spatial Application Uncertainty. | Dissertation. University of California, Santa Barbara | uncertainty | stochastic modelling; uncertainty; | URL |
| Abstract: This dissertation's goal is to establish some practical methodology allowing decision makers to quantitatively describe spatial application uncertainty. Most geographic applications provide a decision maker with single answer, with no supporting information about the reliability of the answer. Describing spatial application uncertainty allows a decision maker to know the range of potential application results. Knowing the range of application results provides a decision maker with an understanding of how much faith to put into the application results using a measure known to the decision maker: the variation of the results itself. This dissertation focuses on how the uncertainty of spatial data affects the uncertainty of spatial applications by applying the following approach: Source maps should include methods for random field generation included in the metadata. Random fields, which provide both a representation of a map's uncertainty magnitude and spatial dependence, perturb probabilistic definitions of maps creating potential map realizations. Potential map realizations provide inputs to geographic information system applications (or any spatial heuristic) by repeatedly running Monte Carlo applications creating a series of potential results. Finally, the data and application's validity is known by analyzing the statistical representation of the potential results. Although computationally expensive, this process is the only practical way of including all forms of analytical heuristics available to map users without explicitly declaring errors for each of these analytical heuristics. This dissertation demonstrates a complete working model of this stochastic simulation process: from describing source map uncertainty to analyzing application uncertainty. Due to the complexity of the problem, this research is still in an exploratory phase, with many parts of the model needing adjustment or better understanding. However, this dissertation provides a working spatial data uncertainty model to the entire research community. |
||||||
BibTeX:
@phdthesis{Ehlschlaeger1998diss,
author = {Ehlschlaeger, Charles Robert},
title = {The Stochastic Simulation Approach: Tools for Representing Spatial Application Uncertainty.},
school = {University of California, Santa Barbara},
year = {1998},
url = {http://www.geog.ucsb.edu/academics/dissertations/dissertations/Ehlschlaeger_Charles_Dissertation_1998.pdf}
}
|
||||||
| Ehlschlaeger, C. R. & Goodchild, M. F. | 1994 | Uncertainty in Spatial Data: Defining, Visualizing, and Managing Data Errors. | Proceedings of GIS/LIS 1994 , 246-53 | uncertainty | ; ; | URL |
| Abstract: There is a considerable body of literature on techniques describing and modeling spatial database uncertainty. Unfortunately, spatial error modeling still isn't available to the general users of spatial databases. Spatial error modeling will only become viable when spatial errors are easily defined, visualized, and made available to spatial applications. Easing spatial error modeling into the user domain will be far easier if error definition, visualization, and management are based on the same fundamental principles. Accordingly, this paper will describe and will demonstrate a suite of public domain tools developed at NCGIA that allow for the definition, visualization, and management of spatial data error in a unified manner. | ||||||
BibTeX:
@inproceedings{Ehlschlaeger1994gislis,
author = {Ehlschlaeger, Charles R. and Goodchild, Michael F.},
title = {Uncertainty in Spatial Data: Defining, Visualizing, and Managing Data Errors.},
booktitle = {Proceedings of GIS/LIS 1994},
year = {1994},
pages = {246-53},
url = {http://www.wiu.edu/users/cre111/older/gislis/gislis.html}
}
|
||||||
| Ehlschlaeger, C. R. & Shortridge, A. M. | 1996 | Modeling Elevation Uncertainty in Geographic Analysis. | Proceeding of the International Symposium on Spatial Data Handling | uncertainty | terrain analysis; uncertainty; DEM; GIS; | URL |
| Abstract: This work uses a stochastic simulation approach to explore the impact of uncertainty in digital elevation data within the context of the least-cost path algorithm. A method for deriving accuracy parameters from higher accuracy data, taking into account the impact of spatial autocorrelation, is explicated. It is demonstrated that the spatial complexity of map generalization, when propagated through non-local GIS operations, can be too problematic to model without employing Monte Carlo stochastic simulation methods explicitly for each application of the operation. | ||||||
BibTeX:
@inproceedings{ehlschlaeger1996issdh,
author = {Ehlschlaeger, Charles R. and Shortridge, Ashton M.},
title = {Modeling Elevation Uncertainty in Geographic Analysis.},
booktitle = {Proceeding of the International Symposium on Spatial Data Handling},
year = {1996},
volume = {9B.15-9B.25},
url = {http://www.wiu.edu/users/cre111/older/SDH96/paper.html}
}
|
||||||
| Ehlschlaeger, C. R., Shortridge, A. M. & Goodchild, M. F. | 1997 | Visualizing spatial data uncertainty using animation. | Computers & Geoscience 23 (4) , 387-395 | uncertainty | Animation; Spatial data; Optimal route; Random fields; DEM ; uncertainty; | URL |
| Abstract: This paper examines methodologies for dynamically displaying information about uncertainty. Modeling uncertainty in elevation data results in the generation of dozens or hundreds of realizations of the elevation surface. Producing animations of these surfaces is an approach to exploratory data visualization that may assist the researcher in understanding the effect of uncertainty on spatial applications as well as in communicating the results of the research to a wider audience. A nonlinear method for interpolation between the surface realizations is introduced which allows for smooth animation while maintaining the surface characteristics prescribed by the uncertainty model. | ||||||
BibTeX:
@article{ehlschlaeger1997cg,
author = {Ehlschlaeger, Charles R. and Shortridge, Ashton M. and Goodchild, Michael F.},
title = {Visualizing spatial data uncertainty using animation.},
journal = {Computers \& Geoscience},
year = {1997},
volume = {23},
number = {4},
pages = {387-395},
url = {http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6V7D-3T7J19D-J-1&_cdi=5840&_orig=browse&_coverDate=05%2F31%2F1997&_sk=999769995&view=c&wchp=dGLbVzb-zSkWW&_acct=C000049009&_version=1&_userid=946230&md5=cafaffa08e90352cd95280ed01498787&ie=f.pdf}
}
|
||||||
| Eineder, M., Breit, H., Adam, N., Holzner, J., Suchandt, S. & Rabus, B. | 2001 | SRTM X-SAR calibration results. | IEEE International Geoscience and Remote Sensing Symposium, 2001. IGARSS'01. 2 , 748-750 | DEM | ; accuracy; | DOI URL |
| Abstract: The paper presents the results of the Shuttle Radar Topography Mission (SRTM) X-band calibration at DLR as of April 2001, the time of writing. While some areas may be subject to further improvement, the overall image will not change significantly. We summarize the various calibration issues, the methods applied and the results obtained. Addressed topics are: Timing calibration, SNR and coherence, motion analysis and instrument phase errors. The qualitative and quantitative effects of the distortions above on the DEM quality are discussed. | ||||||
BibTeX:
@article{Eineder2001IGARSS01,
author = {Eineder, M. and Breit, H. and Adam, N. and Holzner, J. and Suchandt, S. and Rabus, B.},
title = {{SRTM X-SAR} calibration results.},
journal = {IEEE International Geoscience and Remote Sensing Symposium, 2001. IGARSS'01.},
year = {2001},
volume = {2},
pages = {748-750},
url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=976623},
doi = {10.1109/IGARSS.2001.976623}
}
|
||||||
| Endreny, T. A. & Wood, E. F. | 2001 | Representing elevation uncertainty in runoff modelling and flowpath mapping. | Hydrological Processes 15 (12) , 2223-2236 | uncertainty | Dispersal area algorithm; routing; ; overland flow paths; Little Washita, probability model; | DOI |
| Abstract: Vertical inaccuracies in terrain data propagate through dispersal area subroutines to create uncertainties in runoff flowpath predictions. This study documented how terrain error sensitivities in the D8, Multiple Flow (MF), DEMON, D-Infinity and two hybrid dispersal area algorithms, responded to changes in terrain slope and error magnitude. Runoff dispersal areas were generated from convergent and divergent sections of low, medium, and high gradient 64-ha parcels using a 30 m pixel scale control digital elevation model (DEM) and an ensemble of alternative realizations of the control DEM. The ensemble of alternative DEM realizations was generated randomly to represent root mean square error (RMSE) values ranging from 0‚5 to 6 m and spatial correlations of 0 to 0‚999 across 180 m lag distances. Dispersal area residuals, derived by differencing output from control and ensemble simulations, were used to quantify the spatial consistency of algorithm dispersal area predictions. A maximum average algorithm consistency of 85% was obtained in steep sloping convergent terrain, and two map analysis techniques are recommended in maintaining high spatial consistencies under less optimum terrain conditions. A stochastic procedure was developed to translate DEM error into dispersal area probability maps, and thereby better represent uncertainties in runoff modelling and management. Two uses for these runoff probability maps include watershed management indices that identify the optimal areas for intercepting polluted runoff as well as Monte-Carlo-ready probability distributions that report the cumulative pollution impact of each pixel's downslope dispersal area. | ||||||
BibTeX:
@article{endreny2001hp,
author = {Endreny, T. A. and Wood, E. F.},
title = {Representing elevation uncertainty in runoff modelling and flowpath mapping.},
journal = {Hydrological Processes},
year = {2001},
volume = {15},
number = {12},
pages = {2223-2236},
doi = {10.1002/hyp.266}
}
|
||||||
| Engelhardt, H., Humphrey, N., Kamb, B. & Fahnestock, M. | 1990 | Physical conditions at the base of a fast moving Antarctic ice stream. [BibTeX] |
Science 248 (4951) , 57-59 | ISM | ISM; ice streams; flow modelling | |
BibTeX:
@article{engelhardt1990science,
author = {Engelhardt, H. and Humphrey, N. and Kamb, B. and Fahnestock, M.},
title = {Physical conditions at the base of a fast moving Antarctic ice stream.},
journal = {Science},
year = {1990},
volume = {248},
number = {4951},
pages = {57-59}
}
|
||||||
| Epperson, J. F. | 2002 | An Introduction to Numerical Methods and Analysis. [BibTeX] |
John Wiley & Sons, Inc., Chichester | modelling; numeric; analysis; | ||
BibTeX:
@book{epperson2002book,
author = {Epperson, James F.},
title = {An Introduction to Numerical Methods and Analysis.},
publisher = {John Wiley \& Sons, Inc., Chichester},
year = {2002}
}
|
||||||
| Essery, R. | 2003 | Aggregated and distributed modelling of snow cover for a high-latitude basin. | Global and Planetary Change 38 , 115-120 | Subgrid | DOI |
|
| Abstract: A distributed land-surface model is used to simulate the seasonal cycle of snow cover for a high-latitude basin. In comparison with the distributed model, a simulation using surface parameters and meteorological data averaged over the entire basin overestimates the peak snow accumulation and underestimates the duration of snow cover. Dividing the basin into a small number of elevation bands and performing separate simulations for each band greatly improves the results. The improvement is less marked if information on the elevation dependence of vegetation cover and meteorological conditions is not used. Distributed simulations with different models produce a wider range of results than distributed and aggregated simulations with the same model. | ||||||
BibTeX:
@article{Essery2003GPC,
author = {Essery, Richard},
title = {Aggregated and distributed modelling of snow cover for a high-latitude basin.},
journal = {Global and Planetary Change},
year = {2003},
volume = {38},
pages = {115-120},
doi = {10.1016/S0921-8181(03)00013-4}
}
|
||||||
| Essery, R. & Etchevers, P. | 2004 | Parameter sensitivity in simulations of snowmelt. | Journal of Geophysical Research 109 , D20111 | Melt modelling | DOI |
|
| Abstract: A simple snow model with only three parameters (fresh snow albedo, albedo decay rate for melting snow, and surface roughness) is used to simulate snow accumulation and melt at four sites in Europe and North America, and the extent to which the model's parameters can be calibrated against observations is investigated. Results from the model are compared with observations of snow water equivalent (SWE) and the range of results from models that participated in an intercomparison project for the same sites. Good simulations of SWE are obtained by parameter calibration, but sensitivity analyses show that the SWE observations do not contain enough information to uniquely determine parameter values even for this very simple model. Comparisons of simulated snow albedo with observations for two of the sites give stronger constraints on the model parameters, but the model is unable to give good simulations of SWE and albedo simultaneously with a single parameter set, revealing a weakness due to the model's neglect of internal snowpack processes; an enhanced version of the model representing heat storage in the snow performs better in simultaneous simulations of SWE and albedo. In comparison with observations of snow surface temperature, it is found that sensible heat fluxes in low wind speed conditions have to be enhanced to prevent the model from simulating unrealistically low nighttime temperatures at a sheltered site. | ||||||
BibTeX:
@article{Essery2004JGR,
author = {Essery, Richard and Etchevers, Pierre},
title = {Parameter sensitivity in simulations of snowmelt.},
journal = {Journal of Geophysical Research},
year = {2004},
volume = {109},
pages = {D20111},
doi = {10.1029/2004JD005036}
}
|
||||||
| Essery, R. & Marks, D. | 2007 | Scaling and parametrization of clear-sky solar radiation over complex topography. | Journal of Geophysical Research 112 , D10122 | Subgrid | DOI |
|
| Abstract: Solar radiation at the land surface is influenced by slope, aspect, shadows, and obstruction of the sky, all of which vary over a wide range of length scales in regions of complex topography, with important consequences for the surface energy balance. Atmospheric models, however, generally assume the surface to be flat on subgrid scales. For four areas in North America, ranging in latitude from 39N to 69N and in topography from rolling to mountainous, we simulate spatial patterns of clear-sky incoming solar radiation. It is found that distributions of slope components and variations in shaded area with solar elevation can be approximated by simple functions that scale to each of the areas studied. From these results, parametrizations are developed for averages, standard deviations, and distributions of direct-beam and diffuse solar radiation. Results from these parametrizations, and from a modified form of a simpler parametrization presented previously, compare well with statistics from the spatial simulations. The only topographic input required by the parametrizations is the standard deviation of slope components; this parameter is again found to have simple scaling relationships with the resolution and extent of the underlying elevation grid and with the standard deviation of elevation. | ||||||
BibTeX:
@article{Essery2007JGR,
author = {Essery, Richard and Marks, Danny},
title = {Scaling and parametrization of clear-sky solar radiation over complex topography.},
journal = {Journal of Geophysical Research},
year = {2007},
volume = {112},
pages = {D10122},
doi = {10.1029/2006JD007650}
}
|
||||||
| Etzelmüller, B. | 2000 | On the Quantification of Surface Changes using Grid-based Digital Elevation Models (DEMs). | Transactions in GIS 4 (2) , 129-143 | uncertainty | DEM; glacier; topographic parameters; surface change; accuracy; | DOI |
| Abstract: This paper discusses the quantification of vertical surface displacements by means of grid-based digital elevation models (DEMs). The surface changes are quantified by comparing altitude and different topographic parameters, which have a geomorphic significance with respect to surface changes. This paper describes the choice of different spatial calculation techniques, considering DEM accuracy and the propagation of error for the different topographic parameters involved. The techniques are illustrated on two grid-based DEMs from Finsterwalderbreen, a 35 km2 sized valley glacier on south-western Spitzbergen, Norwegian High Arctic. | ||||||
BibTeX:
@article{Etzelmueller2000TIGIS,
author = {{Etzelm\"uller}, Bernd},
title = {On the Quantification of Surface Changes using Grid-based Digital Elevation Models (DEMs).},
journal = {Transactions in GIS},
year = {2000},
volume = {4},
number = {2},
pages = {129-143},
doi = {10.1111/1467-9671.00043}
}
|
||||||
| Evans, B. J. | 1997 | Dynamic display of spatial data-reliability: does it benefit the map user? | Computers & Geoscience 23 (4) , 409-422 | Cartography; Dynamic cartography; GIS; Reliability; Visualization | DOI |
|
| Abstract: As users of maps we are dependent upon their veracity and by extension the reliability of the data they contain. Several research projects have explored possible methods of visually representing data certainty, a kind of metadata; methods considered include depicting the metadata as a map that is separate from the data map, imbedding the metadata into the data map, and creating an interactive environment allowing simultaneous viewing of both data and metadata. A practical consideration, as we develop methods for graphic depiction of data reliability, is the reaction to and acceptance of proposed methods by the map user. This research studied how maps containing graphically depicted reliability information are used. Potential “usability� of the cartographic display of data reliability is explored by the type of map user (novices versus experts, and males versus females) and the type of map use (assessment of map reliability, confidence in data reliability assessments, and ability to judge the proportion of the areas within the map containing highly reliable data). This study addressed these issues by exploring and analyzing subject responses to an interactive cartographic display of data and its level of reliability. The graphic depiction of reliability information was found to be accessible and comprehensible by all subjects; novice or expert, and male or female. Two methods of combining data and reliability information, as a composite static display and as an animation, were both found to be helpful by the subjects tested. Two other methods of obtaining reliability information, a map displaying only reliability information and an interactive “toggling� between the data and reliability information were not found to be as efficient or effective as the combination methods. | ||||||
BibTeX:
@article{Evans1997CG,
author = {Evans, B. J.},
title = {Dynamic display of spatial data-reliability: does it benefit the map user?},
journal = {Computers \& Geoscience},
year = {1997},
volume = {23},
number = {4},
pages = {409-422},
doi = {10.1016/S0098-3004(97)00011-3}
}
|
||||||
| Evans, I. S. | 1984 | Correlation structures and factor analysis in the investigation of data dimensionality: statistical properties of the Wessex land surface, England. [BibTeX] |
International Symposium on Spatial Data Handling , 98-116 | uncertainty | stochastic modelling; topography; uncertainty; | |
BibTeX:
@inproceedings{evans1984symposium,
author = {Evans, I. S.},
title = {Correlation structures and factor analysis in the investigation of data dimensionality: statistical properties of the Wessex land surface, England.},
booktitle = {International Symposium on Spatial Data Handling},
year = {1984},
volume = {1},
pages = {98-116}
}
|
||||||
| Evans, I. S. | 1980 | An integrated system of terrain analysis and slope mapping. [BibTeX] |
Zeitschrift für Geomorphologie Suppl. Bd. 36 , 274-295 | DEM | terrain analysis; ; modelling; derivatives; | |
BibTeX:
@article{Evans1980ZfG,
author = {Evans, I. S.},
title = {An integrated system of terrain analysis and slope mapping.},
journal = {Zeitschrift f\"ur Geomorphologie},
year = {1980},
volume = {Suppl. Bd. 36},
pages = {274-295}
}
|
||||||
| Evans, I. S. & Cox, N. J. | 1999 | Relations between land surface properties: Altitude, slope and curvature. | Lecture Notes in Earth Sciences 78 , 13-45 | DEM | surface modelling terrain analysis; derivatives; | DOI URL |
| Abstract: The land surface is studied in terms of point properties, linear (flow-line and break-line) properties and areal properties. These show considerable structure and within-region predictability: the land surface is not (uni-)fractal but varies along multiple statistical dimensions. The simplest point properties are altitude itself and the first and second order derivatives, slope and curvature, of the altitude surface. Two components of each derivative are of proven value: it is best to separate the vertical (slope gradient and gradient change) from the horizontal (aspect and aspect change). The relationships between these five, some of which are not intuitive, are discussed here with illustrations from Germany. Slope gradient usually varies with altitude, but not monotonically. The strength of the relationship varies, and in dissected plateaus the overall correlation is negative. The effects of mesoclimate (slope climate) mean that geomorphological processes vary with aspect, and there are a number of hypotheses of how this might affect gradient. Such signals are masked by considerable scatter on gradient-aspect plots, and it is important to use appropriate tools for relating linear to circular variables. Surface curvature (convexity taken as positive) is separated into vertical (profile, change of gradient) and horizontal (plan, change of aspect) components. The relationship between these is almost universally positive, but very weak: correlations are around +0.2, whether or not transformations to reduce the effects of extreme values are applied. As might be expected, profile convexity almost universally increases with altitude, although the correlation is rarely stronger than that of gradient with altitude. Plan convexity is least varied (closest to zero) on steep slopes; extreme but real values are found on floodplains. | ||||||
BibTeX:
@article{Evans1999LNES,
author = {Evans, I. S. and Cox, N. J.},
title = {Relations between land surface properties: Altitude, slope and curvature.},
journal = {Lecture Notes in Earth Sciences},
year = {1999},
volume = {78},
pages = {13-45},
url = {http://www.springerlink.com/content/978-3-540-64932-8/},
doi = {10.1007/BFb0009716}
}
|
||||||
| Fabre, A., Letréguilly, A., Ritz, C. & Mangeney, A. | 1995 | Greenland under changing climates: sensitivity experiments with a new three-dimensional ice-sheet model. [BibTeX] |
Annals of Glaciology 21 , 1-7 | ISM, climate | ||
BibTeX:
@article{Fabre1995AGla,
author = {Fabre, Adeline and Letr{\'e}guilly, Anne and Ritz, Catherine and Mangeney, Anne},
title = {Greenland under changing climates: sensitivity experiments with a new three-dimensional ice-sheet model.},
journal = {Annals of Glaciology},
year = {1995},
volume = {21},
pages = {1-7}
}
|
||||||
| Fabre, A., Ramstein, G., Ritz, C., Pinot, S. & Fournier, N. | 1998 | Coupling an AGCM with an ISM to investigate the ice sheets mass balance at the last glacial maximum. | Geophysical Research Letters 25 (4) , 531-534 | ISM | ISM; climate model; mass balance; | |
| Abstract: The aim of this paper is to investigate the consistency between the ice sheets reconstruction at the LGM and the climate simulated by AGCM. In particular, to investigate whether the laurentian and the fennoscandian ice sheets have an equilibrated mass balance, we use two complementary approaches. First we analyze the changes of snow and water budgets over the ice sheets, only using the model results of LGM runs. Second, we use a thermomechanical ice sheet model [Ritz et al., 1997] forced with the AGCM simulated climate, to perform long term runs at finer spatial resolution. Analyzing the results obtained with both approaches, we show that the ice sheet mass balance computed directly from AGCM results may be biaised. Moreover we show, using two versions of the LMD AGCM, that the ice sheet mass balance computed by the ISM is drastically sensitive to the summer surface temperatures simulated by the AGCM. | ||||||
BibTeX:
@article{Fabre1998GRL,
author = {Fabre, Adeline and Ramstein, G. and Ritz, Catherine and Pinot, S. and Fournier, N.},
title = {Coupling an {AGCM with an ISM} to investigate the ice sheets mass balance at the last glacial maximum.},
journal = {Geophysical Research Letters},
year = {1998},
volume = {25},
number = {4},
pages = {531-534}
}
|
||||||
| Fahnestock, M., Abdalati, W., Joughin, I., Brozena, J. & Gogineni, P. | 2001 | High Geothermal Heat Flow, Basal Melt, and the Origin of Rapid Ice Flow in Central Greenland. | Science 294 (5550) , 2338-2342 | ISM | DOI |
|
| Abstract: Age-depth relations from internal layering reveal a large region of rapid basal melting in Greenland. Melt is localized at the onset of rapid ice flow in the large ice stream that drains north off the summit dome and other areas in the northeast quadrant of the ice sheet. Locally, high melt rates indicate geothermal fluxes 15 to 30 times continental background. The southern limit of melt coincides with magnetic anomalies and topography that suggest a volcanic origin. | ||||||
BibTeX:
@article{Fahnestock2001Science,
author = {Fahnestock, Mark and Abdalati, Waleed and Joughin, Ian and Brozena, John and Gogineni, Prasad},
title = {High Geothermal Heat Flow, Basal Melt, and the Origin of Rapid Ice Flow in Central Greenland.},
journal = {Science},
year = {2001},
volume = {294},
number = {5550},
pages = {2338-2342},
doi = {10.1126/science.1065370}
}
|
||||||
| Farr, T. G., Rosen, P. A., Caro, E., Crippen, R., Duren, R., Hensley, S., Kobrick, M., Paller, M., Rodriguez, E., Roth, L., Seal, D., Shaffer, S., Shimada, J., Umland, J., Werner, M., Oskin, M., Burbank, D. & Alsdorf, D. | 2007 | The Shuttle Radar Topography Mission. | Reviews of Geophysics 45 , RG2004 | topography; radar; interferometry | DOI |
|
| Abstract: The Shuttle Radar Topography Mission produced the most complete, highest-resolution digital elevation model of the Earth. The project was a joint endeavor of NASA, the National Geospatial-Intelligence Agency, and the German and Italian Space Agencies and flew in February 2000. It used dual radar antennas to acquire interferometric radar data, processed to digital topographic data at 1 arc sec resolution. Details of the development, flight operations, data processing, and products are provided for users of this revolutionary data set. | ||||||
BibTeX:
@article{Farr2007RGP,
author = {Farr, Tom G. and Rosen, Paul A. and Caro, Edward and Crippen, Robert and Duren, Riley and Hensley, Scott and Kobrick, Michael and Paller, Mimi and Rodriguez, Ernesto and Roth, Ladislav and Seal, David and Shaffer, Scott and Shimada, Joanne and Umland, Jeffrey and Werner, Marian and Oskin, Michael and Burbank, Douglas and Alsdorf, Douglas},
title = {{The Shuttle Radar Topography Mission.}},
journal = {Reviews of Geophysics},
year = {2007},
volume = {45},
pages = {RG2004},
doi = {10.1029/2005RG000183}
}
|
||||||
| Finlayson, D. P. & Montgomery, D. R. | 2003 | Modeling large-scale fluvial erosion in geographic information systems. | Geomorphology 53 , 147-164 | Landscape evolution; GIS; Stream power; Erosion modeling; | DOI URL |
|
| Abstract: Variants of the stream power model have become standard for large-scale erosion modeling in geographic information systems (GIS) because they can be applied over broad areas without the need for detailed knowledge of stream characteristics. GIS-based implementations of the shear stress, stream power per unit length and stream power per unit area models are closely related to one another and related also to empirical sediment yield models derived from continental-scale factor analyses. Based on a detailed examination of the implementation of stream power analyses at the scale of continental mountain ranges, we demonstrate that: (1) the careful selection of a digital elevation model (DEM) projection can minimize length and area distortion when analyzing large portions of the earth (such as the Himalaya or Andes) in the two-dimensional plane of a DEM. (2) The area-discharge proxy frequently employed in GIS-based stream power studies may not be appropriate for rivers that flow through significant rain shadows or climatic zones. (3) Decreasing the resolution of a DEM from 30- to the 900-m typical for studies of large extent decreased the mean slopes of 15 rivers in the Olympic mountains by 65%, increased the mean drainage basin size by 14%, and caused a 17% reduction in median main-stem channel length. (4) The coefficients k, m and n common to different versions of the Stream Power Law are themselves sensitive to grid resolution when determined from an analysis of area–slope plots. (5) Stream power per unit area decreased in the Olympics mountains as grid resolution decreased. |
||||||
BibTeX:
@article{Finlayson2003GM,
author = {Finlayson, David P. and Montgomery, David R.},
title = {Modeling large-scale fluvial erosion in geographic information systems.},
journal = {Geomorphology},
year = {2003},
volume = {53},
pages = {147-164},
url = {http://prism.washington.edu/lc/RIVRBS/finlayson_2003b.pdf},
doi = {10.1016/S0169-555X(02)00351-3}
}
|
||||||
| Fischer, U. H. & Clarke, G. K. C. | 2001 | Review of subglacial hydro-mechanical coupling: Trapridge Glacier, Yukon Territory, Canada. | Quaternary International 86 , 29-43 | ISM | review; hydro-mechanical coupling; | DOI |
| Abstract: The interaction of basal processes with the subglacial drainage system is a critical issue in understanding glacier dynamics. Since the recognition that many glaciers and ice masses overlie soft sediments rather than hard bedrock, much research has been undertaken to investigate how mechanical and hydrological conditions of a deformable substrate control the coupling at the ice bed interface and thus affect fast ice flow and glacier surging. In research undertaken on Trapridge Glacier, a small surge-type glacier in the St. Elias Mountains, Yukon Territory, Canada, we have combined extensive eld investigations using novel measurement techniques and theoretical modelling to study hydromechanical coupling processes. Measurements of subglacial water pressure indicate that the basal water system can be dramatically inhomogeneous, both spatially and temporally. Since ice bed coupling is strongly in uenced by subglacial water pressure, the stresses at the bed are also markedly heterogeneous and are expected to form a patchwork distribution which mimics the pressure distribution of the basal water system. This heterogeneity in the stress eld at the ice bed interface introduces a pronounced variability to the basal motion mechanics. As such, basal sliding and subglacial sediment deformation are not steady and continuous processes. Instead, the variability of the subglacial water system leads to a spatial and temporal interplay of increased ice bed coupling at low water pressures at one site or time withice bed decoupling during rising water pressures at other sites or times. Thus, on the one hand there is downglacier shear deformation of the bed and accumulation of elastic strain in ice and sediment, while on the other hand there is enhanced slip-sliding of the glacier and upglacier shear motion of the bed due to an elastic relaxation of the sediment. | ||||||
BibTeX:
@article{fischer2001qi,
author = {Fischer, Urs H. and Clarke, Garry K. C.},
title = {Review of subglacial hydro-mechanical coupling: {Trapridge Glacier, Yukon Territory, Canada}.},
journal = {Quaternary International},
year = {2001},
volume = {86},
pages = {29-43},
doi = {10.1016/S1040-6182(01)00049-0}
}
|
||||||
| Fisher, P. F. | 2000 | Sorites paradox and vague geographies. | Fuzzy Sets and Systems 113 (1) , 7-18 | GIS; Uncertainty | DOI |
|
| Abstract: The sorites paradox is ranked among the top five paradoxes of philosophy (Sainsbury, Paradoxes, 2nd ed., Cambridge University Press, Cambridge, 1995). It is simply stated as 'what is a heap'. Deriving from the paradox is a definition of vagueness, which is contrary to the Boolean concept of the world implicit in much geographical teaching and thought, and the representation of geographical information in modern geographical information system. The argument of Sorites Paradox is suggested as a test of whether a concept is vague. If that concept is sorites susceptible, then it should be modelled as a vague concept, otherwise a Boolean model may be appropriate. The recognition of whether or not a particular concept is sorites susceptible does not have to influence the methods of analysis. It should merely inform the interpretation, and the investigator and reader should be aware that the outcome of the analysis is only one of a set of possible outcomes, which depends on how the vague concept is crispened. Furthermore, it is argued here that very many geographical phenomena (relations, objects and processes) can be shown to be sorites susceptible, and so vague, both generically and genetically. Vagueness can be addressed by multi-valued logic and applications of fuzzy set theory (the most common method of implementing multi-valued logic) to geography are reviewed. A formal recognition of vagueness in geographical phenomena is long overdue, and should be welcome in geographical analysis and, certainly, in geographical information systems. | ||||||
BibTeX:
@article{Fisher2000FSS,
author = {Fisher, Peter F.},
title = {Sorites paradox and vague geographies.},
journal = {Fuzzy Sets and Systems},
year = {2000},
volume = {113},
number = {1},
pages = {7-18},
doi = {10.1016/S0165-0114(99)00009-3}
}
|
||||||
| Fisher, P. F. | 1999 | Models of uncertainty in spatial data. [BibTeX] |
Geographical information systems: principles, techniques, management and applications. John Wiley & Sons, Inc., Chichester , 191-205 | Uncertainty, GIS | ||
BibTeX:
@incollection{Fisher1999book,
author = {Fisher, Peter F.},
title = {Models of uncertainty in spatial data.},
booktitle = {Geographical information systems: principles, techniques, management and applications.},
publisher = {John Wiley \& Sons, Inc., Chichester},
year = {1999},
pages = {191-205}
}
|
||||||
| Fisher, P. F. | 1998 | Improved Modeling of Elevation Error with Geostatistics. | GeoInformatica 2:3 , 215-233 | Uncertainty, DEM, GIS | Digital Elevation Models; ; modeling; geostatistics; conditional stochastic simulation; viewsheds | URL |
| Abstract: The elevations recorded within digital models are known to be fraught with errors of sampling, measurement and interpolation. Reporting of these errors according to spatial data standards makes several implicit and unacceptable assumptions about the error: it has no spatial distribution, and it is statistically stationary across a region, or even a nation. The approach explored in this paper employs actual elevations measured in ground and aerial survey at higher precision than the elevations in the DEM and recorded on standard paper maps. These high precision elevations are digitized and used to establish the real statistical and spatial distribution of the error. Direct measurements could also have been taken in the field by GPS or any other means of high precision data collection. These high precision elevations are subtracted from values stored in the DEM for approximately the same locations. The distribution of errors specific to the DEM can then be explored, and can be used in the geostatistical method of conditional stochastic simulation to derive alternative realizations of the error modeled and so of the DEM. Multiple versions of the derived products can also be determined. This paper compares the results of using different methods of error modeling. The best method, which gives widely implementable and defensible results, is that based on conditional stochastic simulation. | ||||||
BibTeX:
@article{fisher1998gi,
author = {Fisher, Peter F.},
title = {Improved Modeling of Elevation Error with Geostatistics.},
journal = {GeoInformatica},
year = {1998},
volume = {2:3},
pages = {215-233},
url = {http://www.springerlink.com/media/9a0qb3fexq6wnmd8drwq/contributions/h/p/9/g/hp9g041xt82688j3.pdf}
}
|
||||||
| Fisher, P. F. | 1993 | Algorithm and implementation uncertainty in viewshed analysis. [BibTeX] |
International Journal of Geographical Information Science 7 (4) , 331-347 | uncertainty | DEM; TIN; elevation retrieval; calculation, algorithm; data model; comparison; | |
BibTeX:
@article{Fisher1993IJGIS,
author = {Fisher, Peter F.},
title = {Algorithm and implementation uncertainty in viewshed analysis.},
journal = {International Journal of Geographical Information Science},
year = {1993},
volume = {7},
number = {4},
pages = {331-347}
}
|
||||||
| Fisher, P. F., Cheng, T. & Wood, J. | 2007 | Higher Order Vagueness in Geographical Information: Empirical Geographical Population of Type n Fuzzy Sets. | GeoInformatica 11 (3) , 311-330 | DEM, uncertainty | fuzzy sets - mountains - geomorphometry - type 2 fuzzy sets - vagueness - uncertainty | DOI |
| Abstract: Fuzzy set theory has been suggested as a means for representing vague spatial phenomena, and is widely known for directly addressing some of the issues of vagueness such as the sorites paradox. Higher order vagueness is widely considered a necessary component of any theory of vagueness, but it is not so well known that it too is competently modelled by Type n Fuzzy sets. In this paper we explore the fuzzy representation of higher order vagueness with respect to spatial phenomena. Initially we relate the arguments on philosophical vagueness to Type n Fuzzy sets. As an example, we move on to an empirical generation of spatial Type 2 Fuzzy sets examining the spatial extent of mountain peaks in Scotland. We show that the Type 2 Fuzzy sets can be populated by using alternative parameterisations of a peak detection algorithm. Further ambiguities could also be explored using other parameters of this and other algorithms. We show some novel answers to interrogations of the mountain peaks of Scotland. The conclusion of this work is that higher order vagueness can be populated for Type 2 and higher fuzzy sets. It does not follow that it is always necessary to examine these higher order uncertainties, but a possible advantage in terms of the results of spatial inquiry is demonstrated. | ||||||
BibTeX:
@article{Fisher2007GI,
author = {Fisher, Peter F. and Cheng, Tao and Wood, Joseph},
title = {Higher Order Vagueness in Geographical Information: Empirical Geographical Population of Type n Fuzzy Sets.},
journal = {GeoInformatica},
year = {2007},
volume = {11},
number = {3},
pages = {311-330},
doi = {10.1007/s10707-006-0009-5}
}
|
||||||
| Fisher, P. F., Cheng, T. & Wood, J. | 2004 | Where is Helvellyn? Fuzziness of multi-scale landscape morphometry. | Transactions of the Institute of British Geographers 29 (1) , 106-128 | Uncertainty | fuzzy sets; landforms; morphometry; multi-scale analysis; mountains; Lake District | DOI |
| Abstract: The landscape in which people live is made up of many features, which are named and have importance for cultural reasons. Prominent among these are the naming of upland features such as mountains, but mountains are an enigmatic phenomenon which do not bear precise and repeatable definition. They have a vague spatial extent, and recent research has modelled such classes as spatial fuzzy sets. We take a specifically multiresolution approach to the definition of the fuzzy set membership of morphometric classes of landscape. We explore this idea with respect to the identification of culturally recognized landscape features of the English Lake District. Discussion focuses on peaks and passes, and the results show that the landscape elements identified in the analysis correspond to well-known landmarks included in a place name database for the area, although many more are found in the analysis than are named in the available database. Further analysis shows that a richer interrogation of the landscape can be achieved with Geographical Information Systems when using this method than using standard approaches. | ||||||
BibTeX:
@article{fisher2004transibg,
author = {Fisher, Peter F. and Cheng, Tao and Wood, Joseph},
title = {Where is {Helvellyn? Fuzziness} of multi-scale landscape morphometry.},
journal = {Transactions of the Institute of British Geographers},
year = {2004},
volume = { 29},
number = {1},
pages = {106-128},
doi = {10.1111/j.0020-2754.2004.00117.x}
}
|
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| Fisher, P. F. & Tate, N. J. | 2006 | Causes and consequences of error in digital elevation models. | Progress in Physical Geography 30 (4) , 467-489 | Uncertainty, DEM | ; ; modelling; | DOI URL |
| Abstract: All digital data contain error and many are uncertain. Digital models of elevation surfaces consist of files containing large numbers of measurements representing the height of the surface of the earth, and therefore a proportion of those measurements are very likely to be subject to some level of error and uncertainty. The collection and handling of such data and their associated uncertainties has been a subject of considerable research, which has focused largely upon the description of the effects of interpolation and resolution uncertainties, as well as modelling the occurrence of errors. However, digital models of elevation derived from new technologies employing active methods of laser and radar ranging are becoming more widespread, and past research will need to be re-evaluated in the near future to accommodate such new data products. In this paper we review the source and nature of errors in digital models of elevation, and in the derivatives of such models. We examine the correction of errors and assessment of fitness for use, and finally we identify some priorities for future research. | ||||||
BibTeX:
@article{Fisher2006PPG,
author = {Fisher, Peter F. and Tate, Nicholas J.},
title = {Causes and consequences of error in digital elevation models.},
journal = {Progress in Physical Geography},
year = {2006},
volume = {30},
number = {4},
pages = {467-489},
url = {http://ppg.sagepub.com/cgi/content/refs/30/4/467},
doi = {10.1191/0309133306pp492ra}
}
|
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| Florinsky, I. V. | 2002 | Errors of signal processing in digital terrain modelling. | International Journal of Geographical Information Science 16 (5) , 475-501 | DEM | DEM; error modelling; signal processing; modelling | DOI |
| Abstract: We present new interpretation of three classes of errors in digital terrain models (DTMs) which can be sources of artefacts in DTM-based studies: (a) errors in interpolation of digital elevation models (DEMs) caused by the Gibbs phenomenon; (b) errors in DTM derivation from DEMs with 'enhanced' resolution due to noise increase after DEM differentiation; (c) errors in DTM derivation caused by displacement of a DEM grid. Explanation of artefact roots and ways to avoid them are carried out in the context of the theory of signal processing. The Gibbs phenomenon is a specific behaviour of some functions manifested as over- and undershoots near a jump discontinuity. Any DEM includes jump discontinuities of the elevation, such as escarpments and pronounced errors of DEM generation. There are four main ways to prevent or reduce DEM errors caused by the Gibbs phenomenon: (a) decreasing the jump discontinuity before DEM interpolation; (b) using interpolation functions which do not generate the Gibbs phenomenon; (c) omitting over- and undershoots after DEM interpolation; (d) filtering the Gibbs phenomenon. Derivation of topographic variables from DEMs marked by 'enhanced' resolution can lead to artefacts. If a DEM of this kind is interpolated by triangulation-based algorithms, triangular patterns may be revealed on maps of topographic variables. If an 'enhanced' resolution of DEM is achieved by the weighted average methods of interpolation, contour 'traces' may be seen on maps. This is because partial derivatives used to calculate some topographic variables are very responsive to high-frequency components of a DEM. To prevent these errors one should use a regular DEM with a grid space relating to an average distance between points in an irregular DEM. Displacement of a grid of points, wherein elevation values are interpolated or determined, influences the derivation of topographic variables (e.g. map design of horizontal and vertical curvatures). Some patterns break, merge, and change their width and length. Small dots, lines, and particles of big patterns can appear and disappear on maps. These effects should be taken into account in the application of these maps to DTM-based geological studies. | ||||||
BibTeX:
@article{Florinsky2002IJGIS,
author = {Florinsky, Igor V.},
title = {Errors of signal processing in digital terrain modelling.},
journal = {International Journal of Geographical Information Science},
year = {2002},
volume = {16},
number = {5},
pages = {475-501},
doi = {doi:10.1080/13658810210129139}
}
|
||||||
| Florinsky, I. V. | 1998 | Accuracy of local topographic variables derived from digital elevation models. | International Journal of Geographical Information Science 12 (1) , 47-61 | DEM | DEM, derivatives, accuracy | URL |
| Abstract: We study the accuracy of data on some local topographic attributes derived from digital elevation models (DEMs). First, we carry out a test for the precision of four methods for calculation of partial derivatives of elevations. We find that the Evans method is the most precision algorithm of this kind. Second, we produce formulae for root mean square errors of four local topographic variables (gradient, aspect, horizontal and vertical landsurface curvatures), provided that these variables are evaluated with the Evans method. Third, we demonstrate that mapping is the most convenient and pictorial way for the practical implementation of the formulae derived. A DEM of a part of the Kursk Region (Russia) is used as an example. We find that high errors of data on local topographic variables are typical for flat areas. Results of the study can be used to improve landscape investigations with digital terrain models. | ||||||
BibTeX:
@article{florinsky1998ijgis,
author = {Florinsky, Igor V.},
title = {Accuracy of local topographic variables derived from digital elevation models.},
journal = {International Journal of Geographical Information Science},
year = {1998},
volume = {12},
number = {1},
pages = {47-61},
url = {http://docserver.ingentaselect.com/deliver/cw/tandf/13658816/v12n1/s4/p47.pdf?fmt=dirpdf&tt=158&cl=125&ini=connect&bini=&wis=&ac=0&acs=85001709,982,291412&expires=1110210629&checksum=2C1533211C6BA37339E0F4326B113875&cookie=185470752}
}
|
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| Florinsky, I. V. | 1998 | Combined analysis of digital terrain models and remotely sensed data in landscape investigations. | Progress in Physical Geography 22 (1) , 33-60 | DEM | digital terrain model; remote sensing; topographic effect; image classification; landscape study; DEM; | URL |
| Abstract: This article presents a review of the combined analysis of digital terrain models (DTMs) and remotely sensed data in landscape investigations. The utilization of remotely sensed data with DTMs has become an important trend in geomatics in the past two decades. Models of more than ten quantitative topographic variables are employed as ancillary data in the treatment of images. The article reviews the methods for DTM derivation and the basic problems of DTM operation that are important for handling DTMs with imagery, namely: 1) the choice of a DTM network type; 2) DTM resolution; 3) DTM accuracy; and 4) the precise superimposition of DTMs and images. The processing of remotely sensed data and DTMs in combination is used in the following procedures: 1) the image correction of the topographic effect; 2) the correction of geometric image distortion; 3) image classification; 4) statistical and comparative analyses of landscape data; and 5) three-dimensional landscape modelling. These procedures are applied to solve a wide range of problems in geobotany, geochemistry, soil science, geology, glaciology and other sciences. The joint use of imagery and DTMs can increase the total amount of information extracted from both types of data. The trend has been towards the incorporation of the combined analysis of remotely sensed data and DTMs into mixed environmental models. The following potential applications of the treatment of imagery in association with DTMs are identified: 1) the prediction of the migration and accumulation zones of water, mineral and organic substances moved by gravity along the land surface and in the soil; 2) the investigation of the relationships between topographically expressed geological structures and landscape properties; 3) the improvement of geological engineering in industrial planning (e.g., the construction of nuclear power stations, oil and gas pipelines and canals); and 4) the monitoring of existing industries. Digital models of plan, profile, mean and total accumulation curvatures, and nonlocal and combined topographic attributes should be included in data processing both to solve the problems indicated and to improve the outcome of some regular tasks (for example, the prediction of soil moisture distribution and fault recognition). | ||||||
BibTeX:
@article{Florinsky1998PPG,
author = {Florinsky, Igor V.},
title = {Combined analysis of digital terrain models and remotely sensed data in landscape investigations.},
journal = {Progress in Physical Geography},
year = {1998},
volume = {22},
number = {1},
pages = {33-60},
url = {http://www.ingentaconnect.com/content/arn/pipg/1998/00000022/00000001/art00033}
}
|
||||||
| Foody, G. M. | 2003 | Uncertainty, knowledge discovery and data mining in GIS. [BibTeX] |
Progress in Physical Geography 27 , 113-121 | DOI |
||
BibTeX:
@article{Foody2003PPG,
author = {Foody, Giles M.},
title = {Uncertainty, knowledge discovery and data mining in GIS.},
journal = {Progress in Physical Geography},
year = {2003},
volume = {27},
pages = {113-121},
doi = {10.1191/0309133303pp345pr}
}
|
||||||
| Foody, G. M. & Atkinson, P. M. | 2002 | Uncertainty in Remote Sensing and GIS. [BibTeX] |
John Wiley & Sons, Inc., Chichester | |||
BibTeX:
@book{Foody2002book,
author = {Foody, Giles M. and Atkinson, Peter M.},
title = {Uncertainty in Remote Sensing and GIS.},
publisher = {John Wiley \& Sons, Inc., Chichester},
year = {2002}
}
|
||||||
| Forsström, P. & Greve, R. | 2004 | Simulation of the Eurasian ice sheet dynamics during the last glaciation | Global and Planetary Change 42 , 59-81 | ISM | LGM reconstruction; Ice sheet dynamics; Icebergs; Freshwater; Ice streams | DOI |
| Abstract: The Eurasian Weichselian glaciation is studied with the SICOPOLIS ice-sheet model and UKMO PMIP climate anomaly forcings. A set of sensitivity tests are completed, including runs in cold-ice mode, different positive-degree-day (PDD) factors and modified climatic data-sets. The model set-up with present-day climatology modified by a glacial index brings forth an areally correct Last Glacial Maximum (LGM) extent in the western areas, but the ice-sheet volume is too small compared to reconstructions from rebound rates. Applying modified climate data results in similar extent as indicated by the Quaternary Environment of the Eurasian North (QUEEN) Late Weichselian ice-sheet reconstruction. The simulation results display freshwater fluxes from melting and calving in phase with Heinrich events H3 at 27, H2 at 22, and H1 at 14 ka ago. These peaks correspond to fast flow areas, with main activity at 27 and 22 ka ago in the Nordic Channel area and later in the Bear Island and Storfjorden region. The activity of these areas seems to be shifting from south to north from LGM to the Holocene. The freshwater pulse at 19-18.5 ka could correspond to Dansgaard-Oeschger oscillation, as well as ice volume flux peaks around 18-17 ka ago on the western margin of the ice sheet. | ||||||
BibTeX:
@article{Forsstrom2004GPC,
author = {Forsstr\"om, Pirjo-Leena and Greve, Ralf},
title = {Simulation of the {Eurasian} ice sheet dynamics during the last glaciation},
journal = {Global and Planetary Change},
year = {2004},
volume = {42},
pages = {59-81},
doi = {10.1016/j.gloplacha.2003.11.003}
}
|
||||||
| Gallant, J. & Wilson, J. | 2000 | Primary topographic attributes. [BibTeX] |
Terrain Analysis: Principles and Applications. John Wiley & Sons, Inc., Chichester , 51-85 | DEM | terrain analysis; topography; derivatives; | |
BibTeX:
@incollection{gallant2000inwilson,
author = {Gallant, J.C. and Wilson, J.P.},
title = {Primary topographic attributes.},
booktitle = {Terrain Analysis: Principles and Applications.},
publisher = {John Wiley \& Sons, Inc., Chichester},
year = {2000},
pages = {51-85}
}
|
||||||
| Garotte, L. & Bras, R. L. | 1995 | A distributed model for real-time flood forecasting using digital elevation models. | Journal of Hydrology 167 , 279-306 | Subgrids | ||
| Abstract: A distributed model for real-time rainfall-runoff simulation during floods is presented. The model, called Distributed Basin Simulator (DBSIM) is based on the detailed topographical information provided by Digital Elevation Models (DEM). Basin representation uses the rectangular grid of the DEM. Soil properties, input data and state variables are also represented as data layers using the same scheme. Distributed rainfall input is used to map the topographically driven evolution of saturated areas as the storm progresses. The model applies a kinematic model of infiltration to evaluate local runoff generation in grid elements and accounts for lateral moisture flow between elements and surface flow routing in a simplified manner. Model performance is evaluated through sensitivity analyses and an exercise of model calibration and verification. | ||||||
BibTeX:
@article{Garotte1995JournalofHydrology,
author = {Garotte, Luis and Bras, Rafael L.},
title = {A distributed model for real-time flood forecasting using digital elevation models.},
journal = {Journal of Hydrology},
year = {1995},
volume = {167},
pages = {279-306}
}
|
||||||
| Glen, J. | 1958 | The flow law of ice. [BibTeX] |
International Association of Scientific Hydrology Publication 47 , 169-170 | ISM | ISM; glaciology; | |
BibTeX:
@article{glen1958iashp,
author = {Glen, J.W.},
title = {The flow law of ice.},
journal = {International Association of Scientific Hydrology Publication},
year = {1958},
volume = {47},
pages = {169-170}
}
|
||||||
| & others, G. T. T. | 1999 | The Global Land One-kilometer Base Elevation (GLOBE) Digital Elevation Model, Version 1.0. Digital data base on the World Wide Web (URL: http://www.ngdc.noaa.gov/mgg/topo/globe.html) and CD-ROMs. [BibTeX] |
National Oceanic and Atmospheric Administration, National Geophysical Data Center | DEM | ; GLOBE; | URL |
BibTeX:
@manual{GLOBE1999,
author = {{GLOBE Task Team \& others}},
title = {The Global Land One-kilometer Base Elevation (GLOBE) Digital Elevation Model, Version 1.0. Digital data base on the World Wide Web (URL: http://www.ngdc.noaa.gov/mgg/topo/globe.html) and CD-ROMs.},
year = {1999},
url = {http://www.ngdc.noaa.gov/mgg/topo/globe.html}
}
|
||||||
| Goodchild, M. F. | 1992 | Geographical Information Science. | International Journal of Geographical Information Science 6 (1) , 31-45 | GIS | GIscience; review; GIS; | URL |
| Abstract: Research papers at conferences such as EGIS and the International Symposia on Spatial Data Handling address a set of intellectual and scientific questions which go well beyond the limited technical capabilities of current technology in geographical information systems. This paper reviews the topics which might be included in a science of geographical information. Research on these fundamental issues is a better prospect for long-term survival and acceptance in the academy than the development of technical capabilities. This paper reviews the current state of research in a series of key areas and speculates on why progress has been so uneven. The final section of the paper looks to the future and to new areas of significant potential in this area of research. | ||||||
BibTeX:
@article{goodchild1992ijgis,
author = {Goodchild, Michael F.},
title = {{Geographical Information Science}.},
journal = {International Journal of Geographical Information Science},
year = {1992},
volume = {6},
number = {1},
pages = {31-45},
url = {http://www.geo.unizh.ch/geoweb/info/events/gi_reading_group/ws0304/goodchild1992.pdf}
}
|
||||||
| Goovaerts, P. | 1997 | Geostatistics for Natural Ressources Evalutation. [BibTeX] |
Oxford University Press, Oxford, New York | uncertainty, DEM | ||
BibTeX:
@book{Goovaerts1997book,
author = {Goovaerts, P.},
title = {Geostatistics for Natural Ressources Evalutation.},
publisher = {Oxford University Press, Oxford, New York},
year = {1997}
}
|
||||||
| Gregory, J. & Oerlemans, J. | 1998 | Simulated future sea-level rise due to glacier melt based on regionally and seasonally resolved temperature changes. [BibTeX] |
Nature 391 , 474-477 | ISM | ||
BibTeX:
@article{Gregory1998Nature,
author = {Gregory, J.M. and Oerlemans, J.},
title = {Simulated future sea-level rise due to glacier melt based on regionally and seasonally resolved temperature changes.},
journal = {Nature},
year = {1998},
volume = {391},
pages = {474-477}
}
|
||||||
| Greve, R. | 1997 | Application of a Polythermal Three-Dimensional Ice Sheet Model to the Greenland Ice Sheet: Response to Steady-State and Transient Climate Scenarios. | Journal of Climate 10 (5) , 901-918 | ISM | ISM; sensitivity; greenland; climate; | DOI |
| Abstract: Steady-state and transient climate-change computations are performed with the author's three-dimensional polythermal ice sheet model Simulation Code for Polythermal Ice Sheets for the Greenland Ice Sheet. The distinctive feature of this model is the detailed consideration of the basal temperate ice layer, in which the water content and its impact on the ice viscosity are computed; its transition surface to the cold ice region is accounted for by continuum-mechanical jump conditions on this interface. The simulations presented include steady states subject to a range of physical parameters and two different climates (present and glacial conditions), as well as three types of transient scenarios, namely (i) sinusoidal Milankovic-period forcing, (ii) paleoclimatic forcing from the Greenland Ice Core Project core reconstruction, and (iii) future greenhouse warming forcing. | ||||||
BibTeX:
@article{Greve1997JC,
author = {Greve, Ralf},
title = {Application of a Polythermal Three-Dimensional Ice Sheet Model to the Greenland Ice Sheet: Response to Steady-State and Transient Climate Scenarios.},
journal = {Journal of Climate},
year = {1997},
volume = {10},
number = {5},
pages = {901-918},
doi = {10.1175/1520-0442(1997)010<0901:AOAPTD>2.0.CO;2}
}
|
||||||
| Greve, R. & Hutter, K. | 1995 | Polythermal three-dimensional modelling of the Greenland ice sheet with varied geothermal heat flux [BibTeX] |
Annals of Glaciology 21 , 8-12 | ISM | ||
BibTeX:
@article{Greve1995AGla,
author = {Greve, R. and Hutter, K.},
title = {{Polythermal three-dimensional modelling of the Greenland ice sheet with varied geothermal heat flux}},
journal = {Annals of Glaciology},
year = {1995},
volume = {21},
pages = {8-12}
}
|
||||||
| Griethe, H. & Schumann, H. | 2006 | The Visualization of Uncertain Data: Methods and Problems. [BibTeX] |
Simulation und Visualisierung - SimVis'06 , 143-156 | URL |
||
BibTeX:
@inproceedings{Griethe2006simvis,
author = {Griethe, Henning and Schumann, Heidrun},
title = {The Visualization of Uncertain Data: Methods and Problems.},
booktitle = {Simulation und Visualisierung - SimVis'06},
year = {2006},
pages = {143-156},
url = {http://www.simvis.org/Tagung2006/proceedings/3.3.pdf}
}
|
||||||
| Gudmundsson, G. H., Bauder, A., Lüthi, M., Fischer, U. H. & Funk, M. | 1998 | Estimating rates of basal motion and internal ice deformation from continuous tilt measurements. [BibTeX] |
Annals of Glaciology 28 , 247-?252 | ISM | ||
BibTeX:
@article{gudmundsson1998agla,
author = {Gudmundsson, G. Hilmar and Bauder, Andreas and L\"uthi, Martin and Fischer, Urs H. and Funk, Martin},
title = {Estimating rates of basal motion and internal ice deformation from continuous tilt measurements. },
journal = {Annals of Glaciology},
year = {1998},
volume = {28},
pages = {247-?252}
}
|
||||||
| Guth, P. L. | 2006 | Geomorphometry from SRTM: comparison to NED | Photogrammetric Engineering and Remote Sensing 72 (3) , 269-277 | DEM | geomorphometry; ; SRTM; resolution; accuracy; | URL |
| Abstract: The Shuttle Radar Topography Mission (SRTM) produced near-global 1" and 3" DEMs. The cartographically-derived National Elevation Dataset (NED) provides a mechanism to assess SRTM quality. We compared 12 geomorphometric parameters from SRTM to NED for about 500,000 sample areas over the continental United States. For basic parameters like average elevation or relief, the two data sets correlate very highly. For more derived measures, such as curvature and higher moments (skewness and kurtosis), the correlations are much lower, with some parameters essentially uncorrelated between the two DEMs. Correlations improve after restricting analysis to region with average slopes greater than 5 percent, and the SRTM data set compares more closely to simulated 2" NED than to 1" NED. SRTM has too much noise in flat areas, increasing average slope, while in high relief areas SRTM over smoothes topography and lowers average slopes. The true resolution of 1" SRTM DEMs proves to be no better than 2". Sublements: http://www.usna.edu/Users/oceano/pguth/website/research/srtm_2_ned/srtm_morphometry.htm |
||||||
BibTeX:
@article{Guth2006PERS,
author = {Guth, Peter L.},
title = {Geomorphometry from {SRTM}: comparison to {NED}},
journal = {Photogrammetric Engineering and Remote Sensing},
year = {2006},
volume = {72},
number = {3},
pages = {269-277},
url = {http://www.asprs.org/publications/pers/2006journal/march/abstracts.html}
}
|
||||||
| Hagdorn, M., Hulton, N., Payne, A. J. & Rutt, I. | 2005 | Introducing GLIMMER - a 3D thermo-mechanical ice sheet model. | Geophysical Research Abstracts | ISM | URL |
|
| Abstract: Ice sheets are an integral part of the larger Earth System. They affect atmospheric and oceanic circulation patterns, sea-level change and shape the Earth's surface by erosion, sediment transport and deposition. Many complex models, therefore, require a component to simulate ice sheet behaviour. GLIMMER is a 3D finite-difference thermo-mechanical ice sheet model. It is used for the land-ice component of the GENIE project which aims to develop a unified Earth System Model (ESM). This system is a collaborative effort to create a standard ice sheet model that can be used by other projects. GLIMMER can be used as a standalone model or as a component of an ESM. GLIMMER is developed as a Fortran95 library which can be called from other models that provide boundary conditions. This interface is designed to be as flexible as possible. The GLIMMER project includes example drivers of varying complexity ranging from simple EISMINT-type climate parameterisations to complex couplers linking the ice sheet model with the GENIE ESM. GLIMMER has been tested using the EISMINT-1 and EISMINT-2 benchmarks. The netCDF Climate and Forecast Metadata Convention is used for data input and output. GLIMMER also includes data processing and visualisation utilities. The development of GLIMMER is open. Current snapshots can be obtained from the NeSCForge site which hosts the project. Participation with and contributions to the GLIMMER project are most welcome. |
||||||
BibTeX:
@inproceedings{Hagdorn2005EGU,
author = {Hagdorn, Magnus and Hulton, Nick and Payne, Anthony J. and Rutt, Ian},
title = {Introducing {GLIMMER - a 3D} thermo-mechanical ice sheet model.},
booktitle = {Geophysical Research Abstracts},
year = {2005},
volume = {7-07312},
url = {http://www.geos.ed.ac.uk/homes/mhagdorn/posters/EGU05-J-07312.pdf}
}
|
||||||
| Hagdorn, M., Rutt, I., Payne, T. & Hebeler, F. | 2007 | GLIMMER - The GENIE Land Ice Model with Multiply Enabled Regions - Documentation. http://glimmer.forge.nesc.ac.uk/ [BibTeX] |
Universities of Bristol, Edinburgh and Zurich | ISM | URL |
|
BibTeX:
@manual{GLIMMER2006,
author = {Hagdorn, Magnus and Rutt, Ian and Payne, Tony and Hebeler, Felix},
title = {{GLIMMER} - The GENIE Land Ice Model with Multiply Enabled Regions - Documentation. http://glimmer.forge.nesc.ac.uk/},
year = {2007},
url = {http://xweb.geos.ed.ac.uk/~mhagdorn/glide/glide-doc/glimmer_html.html}
}
|
||||||
| Hagdorn, M. K. M. | 2003 | Reconstruction of the Past and Forecast of the Future European and British Ice Sheets and Associated Sea-Level Change. [BibTeX] |
unpublished PhD thesis University of Edinburgh | ISM | ||
BibTeX:
@phdthesis{hagdorn2003phd,
author = {Hagdorn, Magnus K. M.},
title = {Reconstruction of the Past and Forecast of the Future {European and British} Ice Sheets and Associated Sea-Level Change.},
school = {University of Edinburgh},
year = {2003}
}
|
||||||
| Harding, D. J., Gesch, D. B., Carabajal, C. C. & Luthcke, S. B. | 1999 | Application of the shuttle laser altimeter in an accurarcy assessment of GTOPO30, a global 1-kilometer digital elevation model. | International Archives of Photogrammetry and Remote Sensing. 17-3/W14 , 81-85 | GTOPO30, SRTM, accuracy, | URL |
|
| Abstract: Continental-scale topographic profiles between 28.4° N and S latitudes acquired by the first flight of the Shuttle Laser Altimeter (SLA) experiment are used to evaluate the vertical accuracy of GTOPO30, a global digital elevation model with a grid spacing of approximately 1 km. GTOPO30 is a compilation of eight sources of elevation information, including raster and vector data sets. The mean and standard deviation of SLA to GTOPO30 elevation differences are computed for Africa, southern Asia, central South America, and Australia. Variations in mean differences between continental regions and GTOPO30 sources indicate that there are vertical datum discrepancies incorporated in GTOPO30 on the order of 10 m. Variation in the standard deviation of the differences confirms that raster sources in GTOPO30 are more accurate than vector sources. | ||||||
BibTeX:
@article{harding1999iaprs,
author = {Harding, David J. and Gesch, Dean B. and Carabajal, Claudia C. and Luthcke, Scott B.},
title = {Application of the shuttle laser altimeter in an accurarcy assessment of {GTOPO30}, a global 1-kilometer digital elevation model.},
journal = {International Archives of Photogrammetry and Remote Sensing.},
year = {1999},
volume = {17-3/W14},
pages = {81-85},
url = {http://www.isprs.org/commission3/lajolla/pdf/p81.pdf}
}
|
||||||
| Harrower, M. | 2004 | Representing Uncertainty: Does it Help People Make Better Decisions? [BibTeX] |
UCGIS Workshop: Geospatial Visualization and Knowledge Discovery Workshop. National Conference Center, Landsdowne, VA | URL |
||
BibTeX:
@inproceedings{Harrower2004UCGIS,
author = {Harrower, M.},
title = {Representing Uncertainty: Does it Help People Make Better Decisions?},
booktitle = {UCGIS Workshop: Geospatial Visualization and Knowledge Discovery Workshop.},
year = {2004},
url = {http://www.geography.wisc.edu/~harrower/pdf/uncertainty.pdf}
}
|
||||||
| Hastings, D. A. & Dunbar, P. K. | 1999 | Global Land One-kilometer Base Elevation (GLOBE) Digital Elevation Model, Documentation, Volume 1.0. Key to Geophysical Records Documentation (KGRD) 34. [BibTeX] |
National Oceanic and Atmospheric Administration, National Geophysical Data Center | DEM | URL |
|
BibTeX:
@manual{Hastings1999globe,
author = {Hastings, David A. and Dunbar, Paula K.},
title = {Global Land One-kilometer Base Elevation {(GLOBE)} Digital Elevation Model, Documentation, Volume 1.0. Key to Geophysical Records Documentation {(KGRD)} 34.},
year = {1999},
edition = {1.0},
url = {http://www.ngdc.noaa.gov/mgg/topo/report/index.html}
}
|
||||||
| Hastings, D. A. & Dunbar, P. K. | 1998 | Development and Assessment of the Global Land One-km Base Elevation Digital Elevation Model (GLOBE) | ISPRS Archives 32 (4) , 218-221 | Environmental variables; Global, Database; Topography; GLOBE | URL |
|
| Abstract: The Global Land One-kilometer Base Elevation (GLOBE) digital elevation model is the most thoroughly designed, reviewed, and documented global digital elevation dataset to date. GLOBE was developed by an international group of specialists, cooperating with the Committee on Earth Observation Satellites (CEOS) Working Group on Information Systems and Services (WGISS), International Geosphere-Biosphere Programme's Data and Information System (IGBP-DIS), and IGBP Working Group IV/6. GLOBE comprises a global 30 arc-second latitude-longitude array, with land areas populated with integer elevation data. GLOBE is available on the World Wide Web, and on CD-ROM in a format convenient for image processing and raster geographic information systems (GIS). Full GLOBE documentation is available on the CD-ROM and Website. This paper summarizes some findings made during GLOBE's development. | ||||||
BibTeX:
@article{hastings1998isprs,
author = {Hastings, David A. and Dunbar, P. K.},
title = {Development and Assessment of the {Global Land One-km Base Elevation Digital Elevation Model (GLOBE)}},
journal = {ISPRS Archives},
year = {1998},
volume = {32},
number = {4},
pages = {218-221},
url = {http://www.ngdc.noaa.gov/mgg/topo/isprsdem.html}
}
|
||||||
| Hebeler, F. | 2003 | Methoden zur objektiven Auswahl repräsentativer Untersuchungsstandorte für physiogeographische und bodenkundliche Fragestellungen mittels Geographischer Informationssysteme. [BibTeX] |
Diplomarbeit Geographie Universität Giessen, Institut für Bodenkunde und Bodenerhaltung | representativity, spatial data, | URL |
|
BibTeX:
@mastersthesis{hebeler2003,
author = {Hebeler, Felix},
title = {Methoden zur objektiven Auswahl repr\"asentativer Untersuchungsstandorte f\"ur physiogeographische und bodenkundliche Fragestellungen mittels Geographischer Informationssysteme.},
school = {Universit\"at Giessen, Institut f\"ur Bodenkunde und Bodenerhaltung},
year = {2003},
url = {http://www.geo.unizh.ch/~fhebeler/hebeler2002_geogrthesis.pdf}
}
|
||||||
| Hebeler, F. & Purves, R. S. | in press, | The influence of elevation uncertainty on derivation of topographic indices. | Geomorphology | DEM | digital elevation model (DEM), uncertainty, error modelling, topographic indices, GLOBE, SRTM, TARDEM | URL |
| Abstract: Digital elevation models at a variety of resolutions are being increasingly used in geomorphology, for example in comparing the hypsometric properties of multiple catchments. A considerable body of research has investigated the sensitivity of topographic indices to resolution and algorithms, but little work has been done to address the issue of the introduction of uncertainty to derived products as a result of uncertainty and error in elevation values. By using higher resolution data, of supposed higher accuracy (from the Shuttle Radar Topography Mission), for comparison with the widely used 1km GLOBE data set, error surfaces for three mountainous regions were calculated. Correlation analysis showed that error surfaces related to a range of topographic variables for all three regions. This correlation of error with local topography was used to develop a model of uncertainty including a stochastic component, allowing to perform Monte Carlo Simulations (MCS). MCS runs suggest that global statistics for a range of topographic indices are robust to the introduction of uncertainty. However, the derivation of watersheds and related statistics per watershed (e.g. hypsometry) is shown to vary significantly as a result of the introduced uncertainty. | ||||||
BibTeX:
@article{Hebeler2008GM,
author = {Hebeler, Felix and Purves, Ross S.},
title = {The influence of elevation uncertainty on derivation of topographic indices.},
journal = {Geomorphology},
year = {in press,},
url = {http://www.geo.unizh.ch/~fhebeler/geomorphol_preview.pdf}
}
|
||||||
| Hebeler, F. & Purves, R. S. | in press, | Parameterisation of low resolution melt modelling using hypsometric subgrids and its susceptibility to uncertainty. [BibTeX] |
Hydrological Processes | |||
BibTeX:
@article{Hebeler2008HP,
author = {Hebeler, Felix and Purves, Ross S.},
title = {Parameterisation of low resolution melt modelling using hypsometric subgrids and its susceptibility to uncertainty.},
journal = {Hydrological Processes},
year = {in press,}
}
|
||||||
| Hebeler, F. & Purves, R. S. | 2008 | Modeling DEM Data Uncertainties for Monte Carlo Simulations of Ice Sheet Models. | Quality Aspects in Spatial Data Mining. CRC Press, Boca Raton , 175-196 | DEM, GIS, Uncertainty, ISM | ||
| Abstract: For realistic modelling of digital elevation model (DEM) uncertainty, information on the amount and spatial configuration is needed. However, common DEM products are often distributed with global error figures at best. Where no higher accuracy reference data is available, assumptions have to be made about the spatial distribution of uncertainty, that are often unrealistic. In order to assess the impact of DEM uncertainty on the results of an ice sheet model (ISM) for an area where no higher accuracy reference data was available, we quantified DEM error of comparable regions with available reference data. Deriving good correlation of error magnitude and spatial configuration with DEM characteristics, these dependencies were incorporated into an uncertainty model containing both deterministic and stochastic components. The developed uncertainty model proved to reproduce amount and spatial correlation of DEM error well while producing uncertainty surfaces suitable for Monte Carlo Simulations (MCS). Applying the model to a DEM of Fennoscandia, a MCS was conducted using an ISM during the first 40ka of the Last Glacial Maximum (LGM). Results showed DEM uncertainty to have significant impact on model results during nucleation and retreat of the ice sheet. | ||||||
BibTeX:
@incollection{Hebeler2008CRC,
author = {Hebeler, Felix and Purves, Ross S.},
title = {Modeling {DEM} Data Uncertainties for Monte Carlo Simulations of Ice Sheet Models.},
booktitle = {Quality Aspects in Spatial Data Mining.},
publisher = {CRC Press, Boca Raton},
year = {2008},
pages = {175-196}
}
|
||||||
| Hebeler, F. & Purves, R. S. | 2007 | Estimating the impacts of DEM uncertainty on Ice Sheet Model results. [BibTeX] |
Geophysical Research Abstracts | DEM; ISM; | URL |
|
BibTeX:
@inproceedings{Hebeler2007EGU1,
author = {Hebeler, Felix and Purves, Ross S.},
title = {Estimating the impacts of {DEM} uncertainty on Ice Sheet Model results.},
booktitle = {Geophysical Research Abstracts},
year = {2007},
volume = {9-08333},
url = {http://www.geo.unizh.ch/~fhebeler/EGU2007-A-08333.pdf}
}
|
||||||
| Hebeler, F. & Purves, R. S. | 2007 | Modelling DEM data uncertainties for Monte Carlo Simulations of Ice Sheet Models. [BibTeX] |
Proceedings of the 5th International Symposium on Spatial Data Quality. ITC | GIS | URL |
|
BibTeX:
@inproceedings{Hebeler2007ISSDQ,
author = {Hebeler, Felix and Purves, Ross S.},
title = {Modelling {DEM} data uncertainties for {Monte Carlo} Simulations of Ice Sheet Models.},
booktitle = {Proceedings of the 5th International Symposium on Spatial Data Quality.},
year = {2007},
url = {http://www.itc.nl/issdq2007/proceedings/Session%203%20Applications/paper%20hebeler%5B1%5D.pdf}
}
|
||||||
| Hebeler, F. & Purves, R. S. | 2005 | A comparison of the influence of topographic and mass balance uncertainties on modeled ice sheet extents and volumes. | Eos Trans. AGU (C23A-1154) | ISM | URL |
|
| Abstract: Ice sheet models are an important source of estimates of the impact of future changes of global climate on, for example, sea level. Such models have multiple sources of uncertainty including inputs describing climate forcing, the topography on which this climate acts, and the modeled responses of ice sheets to such forcing. Up until the recent past, most ice sheet models at continental or regional scales have relied on a limited number of sources of elevation data such as those provided at resolutions of the order of kilometers by the USGS (i.e. GLOBE). Previous experiments demonstrated that quoted accuracies in such Digital Elevation Models (DEMs) of between 18m and 150m RMSE have significant impacts on modeled ice sheet extent and volume for a set of Monte Carlo simulations run on Scandinavian topography at a resolution of 20km. The availability of high resolution elevation data at a near global scale provided by the Shuttle Radar Topography Mission (SRTM) provides an excellent opportunity to further explore such uncertainties. In this paper we explore the sensitivity of ice sheet model runs in southern South America to topographic uncertainty, by treating SRTM data as ground truth for comparison with GLOBE. A comparison of STRM with GLOBE data reveals that along the Andean ridge from the Pacific coast to the Amazon basin elevation values are highly biased with various sources of supposed error (for example, data sources of different quality, measurement, interpolation, and systematic errors). Importantly, while the average differences of GLOBE altitudes from corresponding SRTM means are around 30m over the whole area, large patches in the Andean Highlands, where ice sheet inception and growth is likely, show spatially auto-correlated differences of 80-300m. In order to examine the impact these inaccuracies have on ice sheet models, a suite of topographies was produced from the original GLOBE data by adding a random, spatially correlated error surface simulating the observed uncertainties. These modified topographies were then resampled to a resolution of 5km suitable for ice sheet modeling using a bilinear interpolator. This generalisation process is a further source of uncertainty in elevation values. To estimate the influence of this resampling in comparison to uncertainties present in elevation data, SRTM data was generalized to 5km resolution using a range of methods. The variance in suites of generalized DEMs is being used as input for simulation of the Patagonian ice sheet during the first 40k years of the Last Glacial Maximum through Monte Carlo Simulations. Previous experiments have shown that the observed relative variation of modelled ice extent and volume depends on the absolute size of the ice mass and, in Patagonia, it is expected to be of the order of 10%. Variations caused by topographic uncertainty will be compared with the system's sensitivity to variation in mass balance through climate forcing, in order to assess the relative influence of these different terms on uncertainty. |
||||||
BibTeX:
@inproceedings{hebeler2005agu,
author = {Hebeler, Felix and Purves, Ross S.},
title = {A comparison of the influence of topographic and mass balance uncertainties on modeled ice sheet extents and volumes.},
booktitle = {Eos Trans. AGU},
year = {2005},
volume = {86},
number = {C23A-1154},
note = {No 52},
url = {fhebeler_agu05_abstract.pdf}
}
|
||||||
| Hebeler, F. & Purves, R. S. | 2005 | GIS in ice sheet modelling: assessing the impact of topographic uncertainties. [BibTeX] |
Proceedings of the Swiss Geoscience Meeting 2005 | DEM, ISM | URL |
|
BibTeX:
@inproceedings{hebeler2005sgm,
author = {Hebeler, Felix and Purves, Ross S.},
title = {{GIS} in ice sheet modelling: assessing the impact of topographic uncertainties.},
booktitle = {Proceedings of the Swiss Geoscience Meeting 2005},
year = {2005},
url = {http://www.geo.unizh.ch/~fhebeler/fhebeler_sgm05_abstract.pdf}
}
|
||||||
| Hebeler, F. & Purves, R. S. | 2004 | Representation of topography and its role in uncertainty: a case study in ice sheet modelling. | GIScience 2004: Proceedings of the Third International Conference on Geographic Information Science. , 118-121 | DEM, ISM | URL |
|
| Abstract: As elevation and its derivatives are essential inputs for a wide range of process models, topography and its representation in environmental modelling is undoubtedly of key importance and as such has long been recognised in GIScience (e.g. Hutchinson & Gallant, 1999; 2000). Research areas include the variation in derived parameters with resolution, scale, and algorithms (Zhang et al., 1999; Hutchinson & Gallant, 2000), appropriate models of terrain representation (Wood, 1998; Schneider, 2001), generalisation of topographic data (Weibel & Heller, 1991), and others. However, in the main this work has concentrated on socalled primary and composed topography indices (Beven & Moore, 1992), e.g. catchment areas (Hurtrez et al., 1999) or feature extraction at variable scales (Fisher et al., 2004). Sensitivity tests examining the influence of resolution arerelatively common in process modelling, but generally do not explore issues of representation, with some notable exception (Tucker et al., 2001). In this paper the sensitivity of a large scale dynamic process model to topography and its representation is explored. Model intercomparisons are performed as a first step towards developing a set of experiments to explore the uncertainty introduced into a dynamic process model as a result of variations in representation of terrain. The topographies used as model inputs, the experiments chosen to identify the importance of terrain representation, and the model used are described as well as some initial results from these experiments. A primary step in this work is to test model sensitivity to different aspects of terrain representation: resolution, DEM quality, generalisation and smoothing effects, and slope algorithms. As a case study, an ice sheet model (Boulton & Payne, 1992; Purves & Hulton, 2000) is run using a range of natural and artificial DEMs. Ice sheet modelling, in common with most numerical modelling, aims to improve our understanding of the real world through abstractions of reality. In this work we seek to investigate the importance of different abstractions of terrain properties on such models. In ice sheet modelling two key processes - nucleation (the initiation of an ice sheet through the forming of perennial ice) and ablation (the removal of mass from the ice sheet system, usually as melting or calving) - are highly susceptible to aspects of terrain representation. Ice sheet models (ISMs) therefore present an excellent example for sensitivity testing. Also, current ISMs run on resolutions of 5 to 20km, allowing the use of a range of possible higher resolution DEM data sets for the testing of the influence of different methods of terrain generalisation effects. | ||||||
BibTeX:
@inproceedings{hebeler2004giscience,
author = {Hebeler, Felix and Purves, Ross S.},
title = {Representation of topography and its role in uncertainty: a case study in ice sheet modelling.},
booktitle = {GIScience 2004: Proceedings of the Third International Conference on Geographic Information Science.},
year = {2004},
pages = {118-121},
url = {http://www.geo.unizh.ch/~fhebeler/}
}
|
||||||
| Hebeler, F., Purves, R. S., Hagdorn, M. & Hulton, N. R. | 2005 | Experiments on the sensitivity of modelled extent of Fennoscandian icesheet to representation of topography. | Geophysical Research Abstracts | DEM; ISM; | uncertainty; DEM; GLOBE; ISM | URL |
| Abstract: Many ice sheet models (ISM) run at low resolutions of the order of 5-20km for a number of reasons. A number of factors limit resolution, such as model physics, the fact that ISMs are often running at continental and global scales, the limited resolution of climate data available to drive these models and historically, because of the low resolutions of the available digital elevation models (DEM). However, ISMs have been shown to be susceptible to uncertainties in the input data, due to the limited amount of topographic detail at resolutions of 5km and above. Previous work has documented that uncertainties in DEM can significantly affect ISM results due to crisp altitude dependant thresholds of mass balance calculation and resulting impacts on inception. Typically, uncertainties in DEM are perceived to originate from measurement uncertainties, but resampling DEMs to resolutions suitable for ISMs introduces an even larger amount of ambiguity through the oversimplification of terrain, depending on the target and source resolution, the resampling method and terrain attributes. Experiments using a temperature index melt model with an optional enhanced solar radiation component on the European Alps have shown the distribution and absolute amount of potential melt per area to depend on the resolution ranging from 1 to 10km, with significantly higher melt rates at 1km DEM resolution compared to 10km. By introducing DEM uncertainty using a model that simulates uncertainties typically inherent in GLOBE data, as well as the effect of resampling, the amount and distribution of melt is found to distinctly vary. This problem has previously been recognized and addressed, e.g. by using a hypsometric subgrid approach, where subgrids within each DEM cell are internally coupled within the ISM. However, in this work, a simpler and more computationally efficient approach using hypsometric parameterisation is tested for its potential to minimise theimpact of uncertainties in DEM on melt modelling. | ||||||
BibTeX:
@inproceedings{hebeler2005egu,
author = {Hebeler, Felix and Purves, Ross S. and Hagdorn, Magnus and Hulton, Nick R.J.},
title = {Experiments on the sensitivity of modelled extent of {Fennoscandian} icesheet to representation of topography.},
booktitle = {Geophysical Research Abstracts},
year = {2005},
volume = {7-07637},
url = {http://www.geo.unizh.ch/~fhebeler/EGU2007-A-08333.pdf}
}
|
||||||
| Hebeler, F., Purves, R. S. & Jamieson, S. S. R. | accepted | The impact of parametric uncertaintiy analysis and DEM error in ice sheet modelling. [BibTeX] |
Journal of Glaciology | ISM | ||
BibTeX:
@article{Hebeler2008JGla,
author = {Hebeler, Felix and Purves, Ross S. and Jamieson, Stewart S. R.},
title = {The impact of parametric uncertaintiy analysis and DEM error in ice sheet modelling.},
journal = {Journal of Glaciology},
year = {accepted}
}
|
||||||
| Hebeler, F., Purves, R. S., Vetsch, M. & Hoelzle, M. | 2007 | Using hypsometric parameterisation in melt modelling to minimise the impact of DEM uncertainty. | Geophysical Research Abstracts | DEM; ISM | URL |
|
| Abstract: Many ice sheet models (ISM) run at low resolutions of the order of 5-20km for a number of reasons. A number of factors limit resolution, such as model physics, the fact that ISMs are often running at continental and global scales, the limited resolution of climate data available to drive these models and historically, because of the low resolutions of the available digital elevation models (DEM). However, ISMs have been shown to be susceptible to uncertainties in the input data, due to the limited amount of topographic detail at resolutions of 5km and above. Previous work has documented that uncertainties in DEM can significantly affect ISM results due to crisp altitude dependant thresholds of mass balance calculation and resulting impacts on inception. Typically, uncertainties in DEM are perceived to originate from measurement uncertainties, but resampling DEMs to resolutions suitable for ISMs introduces an even larger amount of ambiguity through the oversimplification of terrain, depending on the target and source resolution, the resampling method and terrain attributes. Experiments using a temperature index melt model with an optional enhanced solar radiation component on the European Alps have shown the distribution and absolute amount of potential melt per area to depend on the resolution ranging from 1 to 10km, with significantly higher melt rates at 1km DEM resolution compared to 10km. By introducing DEM uncertainty using a model that simulates uncertainties typically inherent in GLOBE data, as well as the effect of resampling, the amount and distribution of melt is found to distinctly vary. This problem has previously been recognized and addressed, e.g. by using a hypsometric subgrid approach, where subgrids within each DEM cell are internally coupled within the ISM. However, in this work, a simpler and more computationally efficient approach using hypsometric parameterisation is tested for its potential to minimise the impact of uncertainties in DEM on melt modelling. |
||||||
BibTeX:
@inproceedings{Hebeler2007EGU2,
author = {Hebeler, Felix and Purves, Ross S. and Vetsch, Markus and Hoelzle, Martin},
title = {Using hypsometric parameterisation in melt modelling to minimise the impact of {DEM} uncertainty.},
booktitle = {Geophysical Research Abstracts},
year = {2007},
volume = {9-08303},
url = {http://www.geo.unizh.ch/~fhebeler/EGU2007-A-08303.pdf}
}
|
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| Heipke, C., Koch, A. & Lohmann, P. | 2002 | Analysis of SRTM DTM - Methodology and practical results. | Journal of the Swedish Society for Photogrammetry and Remote Sensing: Photogrammetry meets geoinformatics. , 69-80 | DEM | URL |
|
| Abstract: In February 2000 the first mission using space-borne single-pass-interferometry was launched – the Shuttle Radar Topography Mission (SRTM). The goal of the mission was to survey the Earth surface and to generate a homogeneous elevation data set of the world with a grid spacing of 1 arcsec. Antennas with two different wavelengths were used: Beside the American SIR-C the German / Italian X-SAR system was on board. This paper deals with the assessment of the Interferometric Terrain Elevation Data derived from the X-SAR system. These so called ITED-2 data were compared to reference data of higher quality of a well known test site in the south of Hannover (Trigonometric Points and Digital Terrain Model). The approach used is based on a spatial similarity transformation without using any kind of control point information. The algorithm matches the SRTM data onto the reference data in order to derive seven unknown parameters which describe horizontal and vertical shifts, rotations and a scale difference with respect to the reference data. These values describe potentially existing systematic errors. The standard deviation of the SRTM ITED-2 was found to be +- 3,3 m in open landscape, after applying the spatial similarity transformation. Maximum systematic shifts of 4-6 m were detected, representing only 20-25 % of the ITED-2 grid size. In summary, it can be stated that the results are much better than predicted before the start of the mission. Thus, the quality of the SRTM ITED-2 is indeed remarkable. |
||||||
BibTeX:
@inproceedings{Heipke2002jssprs,
author = {Heipke, C. and Koch, A. and Lohmann, P.},
title = {Analysis of {SRTM DTM} - Methodology and practical results.},
booktitle = {Journal of the Swedish Society for Photogrammetry and Remote Sensing: Photogrammetry meets geoinformatics.},
year = {2002},
volume = {2002:1},
pages = {69-80},
url = {http://www.ipi.uni-hannover.de/html/publikationen/2002/koch/0204torlegard.pdf}
}
|
||||||
| Herrington, L. & Pellegrini, G. | 2000 | An advanced shape of country classifier: Extraction of surface features from DEMs. | 4th International Conference on GIS and Environmental Modeling (GIS/EM4). Problems, Prospects and Research Needs. Banff, Alberta, Canada. , 2-8 | Shape of Country; Terrain Analysis; Spatial frequency domain; Filters, ; Smoothing | URL |
|
| Abstract: A number of environmental analyses require the classification of digital elevation models (DEMs) into shape-of-country features. The 10 terrain feature classes used here are ridge, valley, peak, pit, saddle, saddle slope, hill slope, concave slope, convex slope, and flat. These feature classifications are used in hydrological, ecological and other studies. Our specific use is for the development of knowledge based soil property estimators, in particular trafficability analyses, and for the refinement of limited soils information. The technique described here, a combination of surface smoothing in the spatial frequency domain and the determination of the feature class of each cell through the fitting of a mathematical surface to a 3x3 roving window passed over a grid results in 100% of the grids being classified and a classification accuracy of approximately 90%. The Fast Fourier Transform (FFT) is used to produce an image of the DEM in the spatial frequency domain. A low-pass filter with a square wave roll-off in the spatial frequency domain is used to remove high spatial frequency information. This is followed by transformation back into the space domain. The resulting smoothed surface is analyzed by passing a 3x3 roving window over the grid. Eigenvectors, containing all the information needed to represent the feature class of the window, are generated using the Jacobi method from a polynomial representation of the surface in the window. Obtaining the best estimators of the feature class requires that surface cells be classified according to the most significant feature occurring anywhere within the central cell of the window. For example, ridges are more significant than slopes. What we have added to this type of analysis is the determination of the significant features that may occur anywhere in the central cell. Heuristics are then used to refine the classification. The results of applying the classifier to several mathematical surfaces and to real DEMs from Central New York are presented. | ||||||
BibTeX:
@inproceedings{herrington2000gisem4,
author = {Herrington, L. and Pellegrini, G.},
title = {An advanced shape of country classifier: Extraction of surface features from {DEMs}.},
booktitle = {4th International Conference on GIS and Environmental Modeling (GIS/EM4). Problems, Prospects and Research Needs. Banff, Alberta, Canada.},
year = {2000},
pages = {2-8},
url = {http://www.colorado.edu/research/cires/banff/pubpapers/205/}
}
|
||||||
| Heuvelink, G. B. | 1998 | Error Propagation in Environmental Modelling with GIS. [BibTeX] |
Research Monographs in Geographic Information Systems. Taylor & Francis, London | uncertainty, GIS | GIS | |
BibTeX:
@incollection{Heuvelink1998book,
author = {Heuvelink, Gerard B.M.},
title = {Error Propagation in Environmental Modelling with {GIS}.},
booktitle = {Research Monographs in Geographic Information Systems.},
publisher = {Taylor \& Francis, London},
year = {1998}
}
|
||||||
| Heuvelink, G. B., Burrough, P. A. & Stein, A. | 1989 | Propagation of errors in spatial modelling with GIS | International Journal of Geographical Information Science 3 , 303-322 | uncertainty, GIS | DOI |
|
| Abstract: Methods are needed for monitoring the propagation of errors when spatial models are driven by quantitative data stored in raster geographical information systems. This paper demonstrates how the standard stochastic theory of error propagation can be extended and applied to continuously differentiable arithmetic operations (quantitative models) for manipulating gridded map data. The statisticalmethodshave beenprogrammed usingtheTaylor seriesexpansion to approximate the models. Modelinputs are (a) modelcoefficients and their standard errors and (b) maps of continuous variables and the associated prediction errors, whichcan be obtained by optimal interpolation from point data. The model output is a map that is accompanied by a map of prediction errors. The relative contributions of the errors in the inputs (model coefficients, maps of individual variables) can be determined and mapped separately allowing judgments to be made about subsequent survey optimization. The methods are illustrated by two case studies. | ||||||
BibTeX:
@article{Heuvelink1989IJGIS,
author = {Heuvelink, Gerard B.M. and Burrough, Peter A. and Stein, Alfred},
title = {Propagation of errors in spatial modelling with {GIS}},
journal = {International Journal of Geographical Information Science},
year = {1989},
volume = {3},
pages = {303-322},
doi = {10.1080/02693798908941518}
}
|
||||||
| Heuvelink, G. B. M. & Burrough, P. A. | 2002 | Developments in statistical approaches to spatial uncertainty and its propagation. [BibTeX] |
International Journal of Geographical Information Science 16 (2) , 111-113 | GIS, uncertainty | DOI |
|
BibTeX:
@article{Heuvelink2002IJGIS,
author = {Heuvelink, Gerard B. M. and Burrough, Peter A.},
title = {Developments in statistical approaches to spatial uncertainty and its propagation.},
journal = {International Journal of Geographical Information Science},
year = {2002},
volume = {16},
number = {2},
pages = {111-113},
doi = {10.1080/13658810110099071}
}
|
||||||
| Hindmarsh, R. C. | 1993 | Modelling the dynamics of ice sheets. | Progress in Physical Geography 17 (4) , 391-412 | ISM | Ice sheets; ice shelves; modelling | DOI |
| Abstract: Although the mechanics and qualitative dynamics of grounded ice sheets and ice shelves are fairly well understood, this is not true for the transition between the two. In consequence, the existence and nature of any grounding line instability have yet to be established. Further problems are understanding how uncertainties in input parameters affect results, and obtaining optimal techniques for parameter inference using ice-sheet models. | ||||||
BibTeX:
@article{Hindmarsh1993PPG,
author = {Hindmarsh, Richard C.A.},
title = {Modelling the dynamics of ice sheets.},
journal = {Progress in Physical Geography},
year = {1993},
volume = {17},
number = {4},
pages = {391-412},
doi = {10.1177/030913339301700401}
}
|
||||||
| Hindmarsh, R. C. & Payne, A. J. | 1996 | Time step limits for stable solutions of the ice sheet equation. [BibTeX] |
Annals of Glaciology 23 , 74-85 | ISM | ||
BibTeX:
@article{hindmarsh1996agla,
author = {Hindmarsh, Richard C.A. and Payne, Antony J.},
title = {Time step limits for stable solutions of the ice sheet equation.},
journal = {Annals of Glaciology},
year = {1996},
volume = {23},
pages = {74-85}
}
|
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| Hock, R. | 2005 | Glacier melt: a review of processes and their modelling. [BibTeX] |
Progress in Physical Geography 29 (3) , 362-391 | ISM | distributed models • energy balance • glacier melt • modelling • temperature-index models | DOI URL |
BibTeX:
@article{Hock2005PPG,
author = {Hock, Regine},
title = {Glacier melt: a review of processes and their modelling.},
journal = {Progress in Physical Geography},
year = {2005},
volume = {29},
number = {3},
pages = {362-391},
url = {http://intl-ppg.sagepub.com/cgi/content/abstract/29/3/362},
doi = {10.1191/0309133305pp453ra}
}
|
||||||
| Hock, R. | 2003 | Temperature index melt modelling in mountain areas. | Journal of Hydrology 282 , 104-115 | ISM | Temperature index models; Degree-day factor; Melt modelling; Glacier mass balance | DOI |
| Abstract: Temperature index or degree-day models rest upon a claimed relationship between snow or ice melt and air temperature usually expressed in the form of positive temperatures. Since air temperature generally is the most readily available data, such models have been the most widely used method of ice and snow melt computations for many purposes, such as hydrological modelling, ice dynamic modelling or climate sensitivity studies. Despite their simplicity, temperature-index models have proven to be powerful tools for melt modelling, often on a catchment scale outperforming energy balance models. However, two shortcomings are evident: (1) although working well over long time periods their accuracy decreases with increasing temporal resolution; (2) spatial variability cannot be modelled accurately as melt rates may vary substantially due to topographic effects such as shading, slope and aspect angles. These effects are particularly crucial in mountain areas. This paper provides an overview of temperature-index methods, including glacier environments, and discusses recent advances on distributed approaches attempting to account for topographic effects in complex terrain, while retaining scarcity of data input. In the light of an increasing demand for melt estimates with high spatial and temporal resolution, such approaches need further refinement and development. | ||||||
BibTeX:
@article{hock2003jh,
author = {Hock, Regine},
title = {Temperature index melt modelling in mountain areas.},
journal = {Journal of Hydrology},
year = {2003},
volume = {282},
pages = {104-115},
doi = {10.1016/S0022-1694(03)00257-9}
}
|
||||||
| Hock, R. | 1999 | A distributed temperature-index ice- and snowmelt model including potential direct solar radiation. [BibTeX] |
Journal of Glaciology 45 (149) , 101-111 | ISM | snowmelt model | |
BibTeX:
@article{hock1999jgla,
author = {Hock, Regine},
title = {A distributed temperature-index ice- and snowmelt model including potential direct solar radiation.},
journal = {Journal of Glaciology},
year = {1999},
volume = {45},
number = {149},
pages = {101-111}
}
|
||||||
| Hodgson, M. E. | 1998 | Comparison of Angles from Surface Slope/Aspect Algorithms. [BibTeX] |
Cartography & Geographic Information Systems 25 (3) , 173-185 | DEM | ||
BibTeX:
@article{hodgson1998cgis,
author = {Hodgson, M. E.},
title = {Comparison of Angles from Surface Slope/Aspect Algorithms.},
journal = {Cartography \& Geographic Information Systems},
year = {1998},
volume = {25},
number = {3},
pages = {173-185}
}
|
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| Hofton, M., Dubayah, R., Blair, J. & Rabine, D. | 2006 | Validation of SRTM elevations over vegetated and non-vegetated terrain using medium footprint lidar. | Photogrammetric Engineering and Remote Sensing 72 (3) , 279-285 | URL |
||
| Abstract: The Shuttle Radar Topography Mission (SRTM) generated one of the most-complete high-resolution digital topographic data sets of the world to date. The elevations generated by the on-board C-band sensor represent surface elevations in "bare earth" regions, and the elevations of various scatterers such as leaves and branches in other regions. Elevations generated by a medium-footprint (> 10 in diameter) laser altimeter (lidar) system known as NASA's Laser Vegetation Imaging Sensor (LVIS) were used to assess the accuracy of SRTM elevations at study sites of variable relief, and landcover. Five study sites in Maine, Massachusetts, Maryland, New Hampshire, and Costa Rica were chosen where coincident LVIS and SRTM data occur. Both ground and canopy top lidar elevations were compared to the SRTM elevations. In "bare earth" regions, the mean vertical offset between the sRTm elevations and LVIS ground elevations varied with study site and was approximately 0.0 m, 0.5 m, 3.0 m, 4.0 m, and 4.5 m at the MaineMaryland, Massachusetts, New Hampshire, and Costa Rica study sites, respectively. In vegetated regions, the mean vertical offset increased, implying the phase center fell above the ground, and the offset varied by region. The sRTm elevations fell on average approximately 14 in below the LVIS canopy top elevations, except in Costa Rica where they were approximately 8 in below the canopy top. At all five study sites, SRTM elevations increased with increasing vertical extent (i.e., the difference between the LVIS canopy top and ground elevations and analogous to canopy height in vegetated regions). A linear relationship was found sufficient to describe the relationship between the SRTM-LVIS elevation difference and canopy vertical extent | ||||||
BibTeX:
@article{Hofton2006PERS,
author = {Hofton, M.A and Dubayah, R and Blair, J.B and Rabine, D.},
title = {Validation of SRTM elevations over vegetated and non-vegetated terrain using medium footprint lidar.},
journal = {Photogrammetric Engineering and Remote Sensing},
year = {2006},
volume = {72},
number = {3},
pages = {279-285},
url = {http://www.asprs.org/publications/pers/2006journal/march/abstracts.html#}
}
|
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| Holmes, K. W., Chadwick, O. & Kyriakidis, P. C. | 2000 | Error in a USGS 30-meter digital elevation model and its impact on terrain modeling. | Journal of Hydrology 233 , 154-173 | Digital terrain models; ; Spatial distribution; Digital simulation; Geostatistics; Global positioning systems; GPS; ; model; | DOI |
|
| Abstract: Calculations based on US Geological Survey (USGS) digital elevation models (DEMs) inherit any errors associated with that particular representation of topography. We investigated the potential impact of error in a USGS 30 m DEM on terrain analysis over 27 km2. The difference in elevation between 2652 differential Global Positioning Systems measurements and USGS 30-m DEM derived elevations provided the comparative error dataset. Analysis of this comparative error data suggested that although the global (average) error is small, local error values can be large, and also spatially correlated. Stochastic conditional simulation was used to generate multiple realizations of the DEM error surface that reproduce the error measurements at their original locations and sample statistics such as the histogram and semivariogram model. The differences between these alternative error surfaces provide a model of uncertainty for the unknown DEM error spatial distribution. These DEM errors had a significant impact on terrain attributes which compound elevation values of many grid cells (e.g. slope, wetness index, etc.). A case study using terrain modeling demonstrates that the result of error propagation is most dramatic in valley bottoms and along streamlines. | ||||||
BibTeX:
@article{Holmes2000JHyd,
author = {Holmes, Karin W. and Chadwick, O.A. and Kyriakidis, Phaedon C.},
title = {Error in a {USGS 30}-meter digital elevation model and its impact on terrain modeling.},
journal = {Journal of Hydrology},
year = {2000},
volume = {233},
pages = {154-173},
doi = {10.1016/S0022-1694(00)00229-8}
}
|
||||||
| Horn, B. | 1981 | Hill shading and the reflectance map. | Proceedings of the IEEE 69 , 14-47 | DEM | URL |
|
| Abstract: Shaded overlays for maps give the user an immediate appreciation for the surface topography since they appeal to an important visual depth cue. A brief review of the history of manual methods is followed by a discussion of a number of methods that have been proposed for the automatic generation of shaded overlays. These techniques are compared using the reflectance map as a common representation for the dependence of tone or gray level on the orientation of surface elements. | ||||||
BibTeX:
@article{Horn1981ProcIEEE,
author = {Horn, B.K.P.},
title = {Hill shading and the reflectance map.},
journal = {Proceedings of the IEEE},
year = {1981},
volume = {69},
pages = {14-47},
url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1456186}
}
|
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| Hu, Z. & Islam, S. | 1997 | Effects of spatial variability on the scaling of land surface parameterizations. | Boundary-Layer Meteorology 83 , 441-461 | uncertainty | Surface heterogeneity, Scaling, Land-surface parameterization, Scale invariance, Aggregation and disaggregation; parameterization; derivatives; scaling; | URL |
| Abstract: Understanding and modelling physical and dynamical processes over heterogeneous land surfaces have become a central focus of many recent studies. There is a considerable debate, however, over how to represent the effects of spatial heterogeneity in mesoscale and global scale models. Here, a computationally efficient analytical approach is presented to evaluate scaling properties of land surface representations. It is shown that the effects of spatial variability may not be negligible for commonly encountered land surfaces and associated parameterizations. Second-order correction terms involving variances of the parameters and covariances of each pair of land surface parameters are developed to account for the effects of heterogeneity. Using this analytical approach, we show that the detail of spatial heterogeneity may not be important for the infrared radiation and reflected solar radiation from the surface, while sensible and latent heat fluxes are shown to be sensitive to heterogeneity. Assumptions related to different parameterizations for the same physical process could potentially lead to different inferences regarding the influence of spatial heterogeneity. The proposed approach, however, is capable of identifying the role of different parameterizations in estimating the influence of spatial heterogeneity. These analytical results are consistent with the results of several recent numerical and field experiments that deal with the effects of small-scale heterogeneity in land surface characteristics. | ||||||
BibTeX:
@article{hu1997blm,
author = {Hu, Zhenglin and Islam, Shafiqul},
title = {Effects of spatial variability on the scaling of land surface parameterizations.},
journal = {Boundary-Layer Meteorology},
year = {1997},
volume = {83},
pages = {441-461},
url = {http://www.springerlink.com/content/l11512610615m802/fulltext.pdf}
}
|
||||||
| Hubbard, A. | 1999 | High-resolution modeling of the advance of the Younger Dryas ice sheet and its climate in Scotland. | Quaternary Research 52 , 27-43 | ISM | DOI |
|
| Abstract: Ice-sheet modeling tightly constrained by empirical studies provides an effective framework to reconstruct past climatic and environmental conditions. Scotland was severely affected by the abrupt climate change associated with the Younger Dryas Stade, during which an extensive ice sheet formed across the west highlands after a period of ice-free conditions. Here, a quasi-threedimensional, time-dependent ice flow/mass-balance model is developed and applied to Scotland at 1 km resolution. The flow model is based on the driving stress approximation with an additional longitudinal correction term, essential at this scale of operation. Surface mass balance is driven by temperature and precipitation changes and further mass wastage is achieved through an empirically defined calving term. The ice dynamics and massbalance components are coupled through the equation for mass continuity, which is integrated through time over a finitedifference grid which yields the geometric evolution of the ice sheet. Initial experiments reveal the model to be relatively insensitive to internal parameters but highly sensitive to mass balance.Furthermore, these experiments indicate that Scotland is readily susceptible to glaciation with large glaciers building up on the flanks of Ben Nevis after a temperature depression of 2.5?C, under present-day precipitation. The Younger Dryas is modeled using a GRIP temperature series locally adjusted for amplitude and a systematic series of runs enables the isolation of the climate which best matches mapped ice limits. This optimum-fit configuration requires an annual temperature cooling of 8?C and the introduction of substantial westeast and southnorth precipitation gradients of 40 and 50%, respectively, to the present-day regime. Under these conditions, a series of substantial independent regional ice centers develop in agreement with trimline studies and after 550 years the modeled ice sheet closely resembles the maximum limits as indicated by field mapping. However, modeled ice continues to expand beyond 550 yr, in conflict with the mapped ice limits which suggest a prolonged period of stability. This discrepancy may be explained by the onset of extreme aridity ca. 400 yr into the Stade associated with a southern migration of the Polar Front, leading to a reduction in atmospheric circulation which effectively starved the ice sheet of its moisture source, preventing further expansion. Introduction of an additional 20% reduction in precipitation to the optimum-fit regime after 350 yr brings the modeled ice sheet to equilibrium, substantiating this conclusion. | ||||||
BibTeX:
@article{hubbard1999qr,
author = {Hubbard, Alun},
title = {High-resolution modeling of the advance of the {Younger Dryas} ice sheet and its climate in {Scotland.}},
journal = {Quaternary Research},
year = {1999},
volume = {52},
pages = {27-43},
doi = {10.1006/qres.1999.2055}
}
|
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| Hubbard, A., Hein, A. S., Kaplan, M. R., Hulton, N. R. & Glasser, N. | 2005 | A modelling reconstruction of the Last Glacial Maximum ice sheet and its deglaciation in the vicinity of the Northern Patagonian Icefield, South America. | Annals of Glaciology 87 A (2) , 375-391 | ISM | Patagonia, LGM, ISM, ELA, climate, forcing, NPI | URL |
| Abstract: A time-dependent model is used to investigate the interaction between climate, extent and fluctuations of Patagonian ice sheet between 45rc and 48rc S during the last glacial maximum (LGM) and its subsequent deglaciation. The model is applied at 2 km resolution and enables ice thickness, lithospheric response and ice deformation and sliding to interact freely and is perturbed from present day by relative changes in sea level and equilibrium line altitude (ELA). Experiments implemented to identify an LGM configuration compatible with the available empirical record, indicate that a stepped ELA lowering of 750 to 950 m is required over 15000 years to bracket the Fenix I-V suite of moraines at Lago Buenos Aires. However, 900 m of ELA lowering yields an ice sheet which best matches the Fenix V moraine (c. 23000 a BP) and Caldenius' reconstructed LGM limit for the entire modelled area. This optimum LGM experiment yields a highly dynamic, low aspect ice sheet, with a mean ice thickness of c. 1130 m drained by numerous large ice streams to the western, seaward margin and two large, fast-flowing outlet lobes to the east. Forcing this scenario into deglaciation using a re-scaled Vostok ice core record results in an ice sheet that slowly shrinks by 25% to c. 14500 a bp, after which it experiences a rapid collapse, loosing some 85% of its volume in c. 800 years. Its margins stabilize during the Antarctic Cold Reversal after which it shrinks to near present-day limits by 11 000 a bp. | ||||||
BibTeX:
@article{hubbard2005agla,
author = {Hubbard, Alun and Hein, Andrew S. and Kaplan, Michael R. and Hulton, Nick R.J. and Glasser, Neil},
title = {A modelling reconstruction of the {Last Glacial Maximum} ice sheet and its deglaciation in the vicinity of the {Northern Patagonian Icefield, South America.}},
journal = {Annals of Glaciology},
year = {2005},
volume = {87 A},
number = {2},
pages = {375-391},
url = {http://www.blackwell-synergy.com/doi/abs/10.1111/j.0435-3676.2005.00264.x}
}
|
||||||
| Hugentobler, M. | 2004 | Terrain Modelling with Triangle Based Free-Form Surfaces. [BibTeX] |
PhD Dept. of Geography, University of Zurich | DEM | URL |
|
BibTeX:
@phdthesis{hugentobler2004thesis,
author = {Hugentobler, Marco},
title = {Terrain Modelling with Triangle Based Free-Form Surfaces.},
school = {Dept. of Geography, University of Zurich},
year = {2004},
url = {http://www.geo.unizh.ch/gis/services/downloads/phd/hugent/thesis10.pdf}
}
|
||||||
| Hugentobler, M., Purves, R. S. & Schneider, B. | 2004 | Evaluating methods for interpolating continuous surfaces from irregular data: case study. [BibTeX] |
Proccedings of the 11th International Symposium on Spatial Data Handling University of Leicester, 109-124 | |||
BibTeX:
@inproceedings{hugentobler2004sdh,
author = {Hugentobler, Marco and Purves, Ross S. and Schneider, Bernhardt},
title = {Evaluating methods for interpolating continuous surfaces from irregular data: case study.},
booktitle = {Proccedings of the 11th International Symposium on Spatial Data Handling},
year = {2004},
pages = {109-124}
}
|
||||||
| Hulton, N. R., Purves, R. S., McCulloch, R., Sugden, D. E. & Bentley, M. | 2002 | The Last Glacial Maximum and deglacation in southern South America. | Quaternary Science Reviews 21 , 233-241 | ISM | Patagonian ice sheet, ice sheet model, LGM, climate numerical model, | DOI |
| Abstract: This paper models the extent of Patagonian icesheet during the Last Glacial Maximum (LGM) and its subsequent deglacation. It constrains a new coupled icesheet/climate numerical model with empirical evidence and simulates the icesheet at the LGM and at stages of deglaciation. Undder LGM conditions an icesheet with a modelled volume slightly in excess of 500,000 km^3 builds up along the Andes. There is a marked contrast between the maritime and continental flanks of the modelled icesheet, with positive mass balance exceeding 2m in the west and declining tenfold to the east. Modelled ice velocities commonly reach 400 m yr ^-^1 in the western fjords. The model is most sensitive to variations in temperature and a good agreement between modelled ice extent and empirical evidence was achieved by applying a temperature decrease of 6'C relative to present day temperatures with constant wind fields over the model domain. Assuming a stepped start to deglaciation, modeled ice volumes decline sharply, contributing 1.2m to global sea level, 80% of it within 2000 years. The empirical record suggests that such a stepped warming occured around 17,500 - 17,150 cal yr ago. | ||||||
BibTeX:
@article{hulton2002qsr,
author = {Hulton, Nicholas R.J. and Purves, Ross S. and McCulloch, R.D. and Sugden, David E. and Bentley, M.J.},
title = {The {Last Glacial Maximum} and deglacation in southern {South America}.},
journal = {Quaternary Science Reviews},
year = {2002},
volume = {21},
pages = {233-241},
doi = {10.1016/S0277-3791(01)00103-2}
}
|
||||||
| Hulton, N. R., Purves, R. S., McCulloch, R., Sugden, D. E. & Bentley, M. | 1997 | Dynamics of mountain ice caps during glacial cycles: the case of Patagonia. [BibTeX] |
Annals of Glaciology 24 , 81-89 | ISM | ||
BibTeX:
@article{hulton1997agla,
author = {Hulton, Nicholas R.J. and Purves, Ross S. and McCulloch, R.D. and Sugden, David E. and Bentley, M.J.},
title = {Dynamics of mountain ice caps during glacial cycles: the case of Patagonia.},
journal = {Annals of Glaciology},
year = {1997},
volume = {24},
pages = {81-89}
}
|
||||||
| Hulton, N. R. & Sugden, D. E. | 1995 | Modelling mass balance on former maritime ice caps: a Patagonian example. | Annals of Glaciology 21 , 304-310 | ISM | mass balance model; precipitation pattern; wind | DOI |
| Abstract: Ice cap modeling constrained by empirical studies provides an effective way of reconstructing past climates. The former Patagonian ice sheet is in a climatically significant location since it lies athwart the Southern Hemisphere westerlies and responds to the latitudinal migration of climatic belts during glacial cycles. A numerical model of the Patagonian ice cap for the last glacial maximum (LGM) is developed, which is time-dependent and driven by changing the mass balance/altitude relationship. It relies on a vertically integrated continuity model of ice mass solved over a finite difference grid. The model is relatively insensitive to ice flow parameters but highly sensitive to mass balance. The climatic input is adjusted to produce the best fit with the known limits of the ice cap at the LGM. The ice cap extends 1800 km along the Andes and has a volume of 440,000 km3. During the LGM the equilibrium line altitude (ELA) was lower than at present by at least 560 m near latitude 40°S, 160 m near latitude 50°S, and 360 m near latitude 56°S. The latitudinal variation in ELA depression can be explained by an overall fall in temperature of about 3.0°C and the northward migration of precipitation belts by about 5° latitude. Annual precipitation totals may have decreased by about 0.7 m at latitude 50°S and increased by about 0.7 m at latitude 40°S. The ELA rises steeply by up to 4 m per kilometer from west to east as the westerlies cross the Andes and this prevents ice growth to the east. The limited decrease in temperature during the LGM could be related to the modest migration of the Antarctic convergence between South America and the Antarctic Peninsula. | ||||||
BibTeX:
@article{hulton1995ag,
author = {Hulton, Nicholas R.J. and Sugden, David E.},
title = {Modelling mass balance on former maritime ice caps: a {Patagonian} example.},
journal = {Annals of Glaciology},
year = {1995},
volume = {21},
pages = {304-310},
doi = {doi:10.1006/qres.1994.1049}
}
|
||||||
| Hulton, N. R., Sugden, D. E., Payne, A. & Clapperton, C. | 1994 | Glacier modeling and the climate of Patagonia during the last glacial maximum. | Quaternary Research 42 , 1-19 | ISM | ice sheet model | DOI |
| Abstract: Ice cap modeling constrained by empirical studies provides an effective way of reconstructing past climates. The former Patagonian ice sheet is in a climatically significant location since it lies athwart the Southern Hemisphere westerlies and responds to the latitudinal migration of climatic belts during glacial cycles. A numerical model of the Patagonian ice cap for the last glacial maximum (LGM) is developed, which is time-dependent and driven by changing the mass balance/altitude relationship. It relies on a vertically integrated continuity model of ice mass solved over a finite difference grid. The model is relatively insensitive to ice flow parameters but highly sensitive to mass balance. The climatic input is adjusted to produce the best fit with the known limits of the ice cap at the LGM. The ice cap extends 1800 km along the Andes and has a volume of 440,000 km3. During the LGM the equilibrium line altitude (ELA) was lower than at present by at least 560 m near latitude 40deg S, 160 m near latitude 50deg S, and 360 m near latitude 56deg S. The latitudinal variation in ELA depression can be explained by an overall fall in temperature of about 3.0deg C and the northward migration of precipitation belts by about 5deg latitude. Annual precipitation totals may have decreased by about 0.7 m at latitude 50deg S and increased by about 0.7 m at latitude 40deg S. The ELA rises steeply by up to 4 m per kilometer from west to east as the westerlies cross the Andes and this prevents ice growth to the east. The limited decrease in temperature during the LGM could be related to the modest migration of the Antarctic convergence between South America and the Antarctic Peninsula. | ||||||
BibTeX:
@article{hulton1994qr,
author = {Hulton, Nicholas R.J. and Sugden, David E. and Payne, Antony and Clapperton, C.M.},
title = {Glacier modeling and the climate of {Patagonia} during the last glacial maximum.},
journal = {Quaternary Research},
year = {1994},
volume = {42},
pages = {1-19},
doi = {10.1006/qres.1994.1049}
}
|
||||||
| Hulton, N. R., Sugden, D. E. & Purves, R. S. | 2003 | Author's response to the comments by G.Wenzens [BibTeX] |
Quaternary Science Reviews 22 , 755-757 | ISM | URL |
|
BibTeX:
@article{hulton2003qsr,
author = {Hulton, Nicholas R.J. and Sugden, David E. and Purves, Ross S.},
title = {Author's response to the comments by {G.Wenzens}},
journal = {Quaternary Science Reviews},
year = {2003},
volume = {22},
pages = {755-757},
url = {http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6VBC-47FDCWC-1-1&_cdi=5923&_user=946230&_orig=search&_coverDate=03%2F31%2F2003&_sk=999779994&view=c&wchp=dGLbVzb-zSkWW&md5=3f390b1f21e420015455df7cda3ab622&ie=/sdarticle.pdf}
}
|
||||||
| Hunter, G. J. & Goodchild, M. F. | 1997 | Modelling the uncertainty of slope and aspect estimates derived from spatial databases. [BibTeX] |
Geographical Analysis 19 (1) , 35-49 | uncertainty | ; ; derivatives;slope; aspect; modeling; database; | |
BibTeX:
@article{Hunter1997GAnalys,
author = {Hunter, Gary J. and Goodchild, Michael F.},
title = {Modelling the uncertainty of slope and aspect estimates derived from spatial databases.},
journal = {Geographical Analysis},
year = {1997},
volume = {19},
number = {1},
pages = {35-49}
}
|
||||||
| Hunter, G. J. & Goodchild, M. F. | 1995 | Dealing with error in spatial databases: a simple case study. | Photogrammetric Engineering and Remote Sensing 61 (5) , 529-537 | uncertainty | ||
| Abstract: There is now a considerable body of literature on the techniques available for modeling and communicating error in spatial databases. Some error models have solid statistical foundations, while the basis for others is not so strong. In this paper, three basic approaches to the problem are examined. The application investigated is a fundamental one - to determine the position of a given terrain elevation value and to portray the resultant error of the answer. Such a problem can be of critical concern to communities in cases of flood plain mapping, determination of rising sea levels resulting from global warming, or delineation of the full supply level for a proposed reservoir. In this instance, the authors suggest that the application of simple probability theory, when combined with the error estimates supplied by data producers and current computer graphics capabilities, can provide users with more meaningful in form ation concerning the error of their spatial database products. In turn, this information may allow them to better deal with an issue of growing concern. | ||||||
BibTeX:
@article{Hunter1995PERS,
author = {Hunter, Gary J. and Goodchild, Michael F.},
title = {Dealing with error in spatial databases: a simple case study.},
journal = {Photogrammetric Engineering and Remote Sensing},
year = {1995},
volume = {61},
number = {5},
pages = {529-537}
}
|
||||||
| Hurtrez, J. E., Sol, C. & Lucazeau, F. | 1999 | Effect of drainage area on hypsometry from an analysis of small-scale drainage basins in the Siwalik hills (central Nepal). | Earth Surface Processes and Landforms 24 , 799-808 | DEM | hydrology; terrain analysis; | URL |
| Abstract: Hypsometry of drainage basins (area±elevation analysis) has generally been used to infer the stage of geomorphic development and to study the influence of varying forcing factors (i.e. tectonics, climate, lithology) on topography. However, the scale dependence of hypsometry has generally been neglected. In order to assess the scale dependence of hypsometry, this study focuses on the sensitivity of hypsometry to different Digital Elevation Model(DEM)resolutions and on the influence of drainage area. Hypsometry inferred from differentDEMsis shown to be robust against variations of their resolution. However, hypsometry appears to be dependent on drainage area. We propose that this scale dependence may reflect the varying importance of river and hillslope processes with basin area. | ||||||
BibTeX:
@article{hurtrez1999espl,
author = {Hurtrez, J. E. and Sol, C. and Lucazeau, F.},
title = {Effect of drainage area on hypsometry from an analysis of small-scale drainage basins in the {Siwalik hills (central Nepal)}.},
journal = {Earth Surface Processes and Landforms},
year = {1999},
volume = { 24},
pages = {799-808},
url = {http://www3.interscience.wiley.com/cgi-bin/abstract/63003654/ABSTRACT}
}
|
||||||
| Hutchinson, M. & Gallant, J. | 2000 | Digital Elevation Models and representation of terrain shape. [BibTeX] |
Terrain Analysis: Principles and Applications. John Wiley & Sons, Inc., Chichester , 29-50 | DEM | ||
BibTeX:
@incollection{hutchinson2000book,
author = {Hutchinson, M.F. and Gallant, J.C.},
title = {Digital Elevation Models and representation of terrain shape.},
booktitle = {Terrain Analysis: Principles and Applications.},
publisher = {John Wiley \& Sons, Inc., Chichester},
year = {2000},
pages = {29-50}
}
|
||||||
| Hutchinson, M. & Gallant, J. | 1999 | Representation of terrain. [BibTeX] |
Geographical Information Systems: Principles and Technical Issues. John Wiley & Sons, Inc., Chichester , 105-124 | DEM | ||
BibTeX:
@incollection{hutchinson1999book,
author = {Hutchinson, M.F. and Gallant, J.C.},
title = {Representation of terrain.},
booktitle = {Geographical Information Systems: Principles and Technical Issues.},
publisher = {John Wiley \& Sons, Inc., Chichester},
year = {1999},
volume = {1},
pages = {105-124}
}
|
||||||
| Hutchinson, M. F. | 1993 | Development of a continent-wide DEM with applications to terrain and climate analysis. [BibTeX] |
Environmental Modeling with GIS. Oxford University Press , 392-399 | DEM | ||
BibTeX:
@incollection{hutchinson1993inbook,
author = {Hutchinson, M. F.},
title = {Development of a continent-wide DEM with applications to terrain and climate analysis. },
booktitle = {Environmental Modeling with GIS.},
publisher = {Oxford University Press},
year = {1993},
pages = {392-399}
}
|
||||||
| Hutter, K. | 1983 | Theoretical Glaciology. Mathematical Approaches to Geophysics. [BibTeX] |
D. Reidel Publishing Company, Dordrecht, Boston, Lancaster | |||
BibTeX:
@book{Hutter1983book,
author = {Hutter, K.},
title = {Theoretical Glaciology. Mathematical Approaches to Geophysics.},
publisher = {D. Reidel Publishing Company, Dordrecht, Boston, Lancaster},
year = {1983}
}
|
||||||
| Huybrechts, P. | 2004 | Mass balance of the cryosphere: observations and modelling of contemporary and future changes. [BibTeX] |
Cambridge University Press, Cambridge , 491-523 | ISM | ||
BibTeX:
@inbook{Huybrechts2004inbook,
author = {Huybrechts, Philippe},
title = {Mass balance of the cryosphere: observations and modelling of contemporary and future changes.},
publisher = {Cambridge University Press, Cambridge},
year = {2004},
pages = {491-523}
}
|
||||||
| Huybrechts, P. | 1998 | Report of the Third EISMINT Workshop on Model Intercomparison. [BibTeX] |
European Science Foundation (Strasbourg), 120 p. | ISM | URL |
|
BibTeX:
@techreport{Huybrechts1998report,
author = {Huybrechts, Philippe},
title = {{Report of the Third EISMINT Workshop on Model Intercomparison.}},
year = {1998},
url = {http://homepages.vub.ac.be/~phuybrec/pdf/EISMINT3.Huyb.1998.pdf}
}
|
||||||
| Huybrechts, P. | 1990 | A 3-D model for the Antarctic ice sheet: a sensitivity study on the glacial-interglacial contrast. [BibTeX] |
Climate Dynamics 5 , 79-92 | ISM | ice sheet model; ice shelf; grounded ice; bed deformation; thermo-mechanical model; sensitivity; | URL |
BibTeX:
@article{huybrechts1990cd,
author = {Huybrechts, Philippe},
title = {{A 3-D model for the Antarctic ice sheet: a sensitivity study on the glacial-interglacial contrast.}},
journal = {Climate Dynamics},
year = {1990},
volume = {5},
pages = {79-92},
url = {http://www.springerlink.com/content/mk410g6012216158/}
}
|
||||||
| Huybrechts, P. | 1986 | A three-dimensional time-dependant numerical model for polar ice sheets; some basic testing with a stable and efficient finite difference scheme. [BibTeX] |
Geografisch Instituut, Vrije Universiteit Brussel, Belgium | ISM | ||
BibTeX:
@techreport{huybrechts1986tech,
author = {Huybrechts, Philippe},
title = {A three-dimensional time-dependant numerical model for polar ice sheets; some basic testing with a stable and efficient finite difference scheme.},
year = {1986}
}
|
||||||
| Huybrechts, P., Gregory, J., Janssens, I. & Wild, M. | 2004 | Modelling Antarctic and Greenland volume changes during the 20th and 21st centuries forced by GCM time slice integrations [BibTeX] |
Elsevier Global and Planetary Change 42 (1-4) , 83-105 | ISM | ||
BibTeX:
@article{Huybrechts2004GPC,
author = {Huybrechts, Philippe and Gregory, Jonathan and Janssens, Ives and Wild, Martin},
title = {{Modelling Antarctic and Greenland volume changes during the 20th and 21st centuries forced by GCM time slice integrations}},
journal = {Global and Planetary Change},
publisher = {Elsevier},
year = {2004},
volume = {42},
number = {1-4},
pages = {83-105}
}
|
||||||
| Huybrechts, P. & Le Meur, E. | 1999 | Predicted present-day evolution patterns of ice thickness and bedrock elevation over Greenland and Antarctica. [BibTeX] |
Polar Research 18 (2) , 299-306 | ISM | ||
BibTeX:
@article{Huybrechts1999PolarResearch,
author = {Huybrechts, P. and Le Meur, E.},
title = {Predicted present-day evolution patterns of ice thickness and bedrock elevation over {Greenland and Antarctica.}},
journal = {Polar Research},
year = {1999},
volume = {18},
number = {2},
pages = {299-306}
}
|
||||||
| Huybrechts, P., Letréguilly, A. & Reeh, N. | 1991 | The Greenland ice sheet and greenhouse warming. | Global and Planetary Change 3 (4) , 399-412 | ISM | URL |
|
| Abstract: Increased melting on glaciers and ice sheets and rising sea level are often mentioned as important aspects of the anticipated greenhouse warming of the earth's atmosphere. This paper deals with the sensitivity of Greenland's ice mass budget and presents a tentative projection of the Greenland component of future sea level rise for the next few hundred years. To do this, the `Villach II temperature scenario' is prescribed, and output from a comprehensive mass balance model is used to drive a high-resolution 3-D thermomechanic model of the ice sheet. The mass balance model consists of two parts: the accumulation part is based on presently observed values and is forced by changes in mean annual air temperature. The ablation model is based on the degree-day method and accounts for the daily and annual temperature cycle, a different degree-day factor for ice and snow melting and superimposed ice formation. Under present-day climatic conditions, the following total mass balance results (in ice equivalent per years): 599.3 x 10 super(9) m super(3) of accumulation, 281.7 x 10 super(9) m super(3) of runoff and assuming a balanced budget, 317.6 x 10 super(9) m super(3) of iceberg calving. A 1K uniform warming is then calculated to increase the runoff by 119.5 x 10 super(9) m super(3). Since accumulation also increases by 32 x 10 super(9) m super(3), this leads to reduction of the total mass balance by 87.5 x 10 super(9) m super(3) of ice, corresponding to a sea level rise of 0.22 mm/yr. For a temperature increase larger than 2.7 K, runoff exceeds accumulation, and if ice sheet dynamics were to remain unchanged, this would add an extra amount of 0.8 mm/yr to the worlds' oceans. Imposing the Villach II scenario (warming up to 4.2 K) and accumulating mass balance changes forward in time (static response) would then result in a global sea level rise of 7.1 cm by 2100 AD, but this figure may go up to as much as 40 cm per century in case the warming is doubled. In a subsequent dynamic model run involving the ice flow, the ice sheet is found to produce a counteracting effect by dynamically producing steeper slopes at the margin, thereby reducing the area over which runoff can take place. This effect is particularly apparent in the northeastern part of the ice sheet, and is also more pronounced for the smaller temperature perturbations. Nevertheless, all these experiments certainly highlight the vulnerability of the Greenland ice sheet with respect to a climatic warming (DBO). | ||||||
BibTeX:
@article{Huybrechts1991GPC,
author = {Huybrechts, Philippe and Letr{\'e}guilly, A. and Reeh, N.},
title = {The {Greenland} ice sheet and greenhouse warming.},
journal = {Global and Planetary Change},
year = {1991},
volume = {3},
number = {4},
pages = {399-412},
url = {http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=4049227&q=&uid=&setcookie=yes}
}
|
||||||
| Huybrechts, P. & Oerlemans, J. | 1988 | Evolution of the East Antarctic ice sheet: a numerical study of thermo-mechanical response patterns with changing climate. [BibTeX] |
Annals of Glaciology 11 , 52-59 | ISM | ||
BibTeX:
@article{huybrechts1988agla,
author = {Huybrechts, Philippe and Oerlemans, J.},
title = {Evolution of the East Antarctic ice sheet: a numerical study of thermo-mechanical response patterns with changing climate.},
journal = {Annals of Glaciology},
year = {1988},
volume = {11},
pages = {52-59}
}
|
||||||
| Huybrechts, P., Payne, A., Abe-Ouchi, A., Calov, R., Fabre, A., Fastook, J., Greve, R., Hindmarsh, R., Hoydal, O. & Jóhannesson, T. | 1996 | The EISMINT benchmarks for testing ice-sheet models. | Annals of Glaciology 23 , 1-12 | ISM | ice sheet model; | URL |
| Abstract: A series of benchmark experiments are presented designed for testing and comparing numerical ice sheet models. Following the outcome of two EISMINT workshops organized for this purpose, model experiments are described for ice sheets under fixed margin as well as under moving margin conditions. These address both steady-state and time-dependent behaviour under schematic boundary conditions and with prescribed physics. The emphasis is on numerical aspects and on comparing results in situations where analytical solutions do not exist. Most of the large-scale ice-sheet models currently in operation were subjected to these tests, and a comparison was made of basic geophysical variables such as ice thickness, velocity and temperature. Here we present the consensus results which emerged, thereby providing reference solutions against which the accuracy and consistency of ice-sheet modeling codes can be assessed. | ||||||
BibTeX:
@article{huybrechts1996agla,
author = {Huybrechts, Philippe and Payne, Antony and Abe-Ouchi, Ayako and Calov, R. and Fabre, A. and Fastook, J.L. and Greve, R. and Hindmarsh, R.C.A. and Hoydal, O. and J\'ohannesson, T.},
title = {The {EISMINT} benchmarks for testing ice-sheet models.},
journal = {Annals of Glaciology},
year = {1996},
volume = {23},
pages = {1-12},
url = {http://www.ggy.bris.ac.uk/personal/TonyPayne/pdfs/eismint_aglac_1996.pdf}
}
|
||||||
| Huybrechts, P. & de Wolde, J. | 1999 | The dynamic response of the Greenland and Antarctic ice sheets to multiple-century climatic warming. | Journal of Climate 12 (8) , 2169-2188 | ISM | ice sheet model | |
| Abstract: New calculations were performed to investigate the combined response of the Greenland and Antarctic ice sheets to a range of climatic warming scenarios over the next millennium. Use was made of fully dynamic 3D thermomechanic ice sheet models, which were coupled to a two-dimensional climate model. The experiments were initialized with simulations over the last two glacial cycles to estimate the present evolution and were subsequently forced with temperature scenarios resulting from greenhouse emission scenarios which assume equivalent CO2 increases of two, four, and eight times the present (1990 A.D.) value by the year 2130 A.D. and a stabilization after that. The calculations brought to light that during the next century (short-term effect), the background evolution trend would dominate the response of the Antarctic ice sheet but would be negligible for the Greenland ice sheet. On that timescale, the Greenland and Antarctic ice sheets would roughly balance one another for the middle scenario (similar to the IPCC96 IS92a scenario), with respective contributions to the worldwide sea level stand on the order of about ?10 cm. On the longer term, however, both ice sheets would contribute positively to the worldwide sea level stand and the most important effect would come from melting on the Greenland ice sheet. Sensitivity experiments highlighted the role of ice dynamics and the height?mass-balance feedback on the results. It was found that ice dynamics cannot be neglected for the Greenland ice sheet, not even on a century timescale, but becomes only important for Antarctica on the longer term. The latter is related to an increased outflow of ice into the ice shelves and to the grounding-line retreat of the west Antarctic ice sheet, which are both found to be sensitive to basal melting below ice shelves and the effective viscosity of the ice shelves. Stretching parameters to their limits yielded a combined maximum rate of sea level rise of 85 cm century?1, of which 60 cm would originate from the Greenland ice sheet alone. | ||||||
BibTeX:
@article{huybrechts1999jc,
author = {Huybrechts, Philippe and de Wolde, Jan},
title = {The dynamic response of the {Greenland and Antarctic} ice sheets to multiple-century climatic warming.},
journal = {Journal of Climate},
year = {1999},
volume = {12},
number = {8},
pages = {2169-2188}
}
|
||||||
| IAHS(ICSI)/UNEP/UNESCO/WMO | 2001 | Glacier mass balance bulletin [BibTeX] |
World Glacier Monitoring Service, University and ETH Zurich. | ISM | glaciology; | URL |
BibTeX:
@book{wgms2001book,
author = {IAHS(ICSI)/UNEP/UNESCO/WMO },
title = {Glacier mass balance bulletin},
publisher = {World Glacier Monitoring Service, University and ETH Zurich.},
year = {2001},
url = {http://www.geo.unizh.ch/wgms/mbb/mbb6/MBB6.pdf}
}
|
||||||
| IPCC | 2007 | Intergovernmental Panel on Climate Change - Fourth Assessment Report: Climate Change 2007 - Working Group II: Impacts, Adaptation and Vulnerability. [BibTeX] |
Intergovernmental Panel on Climate Change, United Nations, Geneve | |||
BibTeX:
@book{IPCC2007,
author = {{IPCC}},
title = {Intergovernmental Panel on Climate Change - Fourth Assessment Report: Climate Change 2007 - Working Group II: Impacts, Adaptation and Vulnerability.},
publisher = {Intergovernmental Panel on Climate Change, United Nations, Geneve},
year = {2007}
}
|
||||||
| IPCC | 2006 | Intergovernmental Panel on Climate Change Data Distribution Center: The Climatic Research Unit Global Climate Dataset - mean 1961-90 climatology. [BibTeX] |
||||
BibTeX:
@misc{IPCC2007data,
author = {{IPCC}},
title = {Intergovernmental Panel on Climate Change Data Distribution Center: The Climatic Research Unit Global Climate Dataset - mean 1961-90 climatology.},
year = {2006}
}
|
||||||
| James, T. D., Carbonneau, P. E. & Lane, S. N. | 2007 | Investigating the Effects of DEM Error in Scaling Analysis. | Photogrammetric Engineering and Remote Sensing 73 (1) , 67-78 | DEM | ||
| Abstract: Digital elevation models (DEMs) are prone to error that, as they can never be entirely eliminated, must be managed effectively. Thus, it is important to understand the nature of error and their sources, especially in the context of the intended use of a DEM. This paper investigates the effects that can be expected when common DEM errors propagate through a scaling analysis. The errors investigated include those associated with perturbation of camera exterior orientation parameters, focal length, and DEM image coordinates, which were simulated numerically. The role of detrending was also investigated. Scaling analysis, by way of the fractal dimension, using a new two-dimensional approach was carried out on a variety of surfaces before and after the introduction of error and the application of detrending. The results reveal some serious procedural implications on scaling analysis and cast doubt on the authenticity of some scaling analysis results in the absence of robust quality assessment and of independent supporting evidence. |
||||||
BibTeX:
@article{James2007PERS,
author = {James, Timothy D. and Carbonneau, Patrice E. and Lane, Stuart N.},
title = {Investigating the Effects of DEM Error in Scaling Analysis.},
journal = {Photogrammetric Engineering and Remote Sensing},
year = {2007},
volume = {73},
number = {1},
pages = {67-78}
}
|
||||||
| Jamieson, S. S. R., Hulton, N. R. J. & Hagdorn, M. | 2008 | Modelling landscape evolution under ice sheets. | Geomorphology 97 (1-2) , 91-108 | ISM | DOI |
|
| Abstract: We use an ice sheet model (GLIMMER) with an erosion component to examine the evolution of landscapes under ice sheets over long time scales in hypothetical situations. GLIMMER is a fully coupled thermomechanical 3-dimensional ice sheet model with a sliding component. The model thus has the ability to predict ice thickness, the distribution of areas at pressure melting point and basal velocities. The erosion rate is assumed to be a simple linear function of the basal velocity and therefore erosion only occurs where the bed is not frozen and basal sliding is possible. In addition, sliding velocities are assumed to be related to basal water production, thus giving a mechanism for smooth temporal and spatial transitions between eroding and non-eroding portions of the bed. The eroding glacial landscape system is modelled for long-term persistent glaciation assuming a variety of initial landscapes. Results indicate that without the inclusion of basal water production in the calculation of sliding velocities, any thermal feedbacks are exaggerated because of steep horizontal basal temperature gradients. Additionally, bed morphology exerts a greater influence under low basal slip conditions because ice cannot respond readily to thermal instabilities. We suggest that erosion and valley overdeepening may aid stabilisation of the thermal regime of an ice sheet and that it is possible to generate glacial signals in previously fluvial systems after only 100 kyr of glaciation at conservative erosion rates. | ||||||
BibTeX:
@article{Jamieson2008GM,
author = {Jamieson, Stewart S. R. and Hulton, Nicholas R. J. and Hagdorn, Magnus},
title = {Modelling landscape evolution under ice sheets.},
journal = {Geomorphology},
year = {2008},
volume = {97},
number = {1-2},
pages = {91-108},
doi = {10.1016/j.geomorph.2007.02.047}
}
|
||||||
| Jamieson, S. S. R., Sinclair, H., Kirstein, L. & Purves, R. S. | 2004 | Tectonic forcing of longitudinal valleys in the Himalaya: morphological analysis of the Ladakh Batholith, North India. | Geomorphology 58 (1) , 49-65 | uncertainty | Ladakh; Himalayas; ; Indus; Longitudinal valley; Morphometric analysis | DOI |
| Abstract: Longitudinal valleys form first order topographic features in many mountain belts. They are commonly located along faults that separate tectonic zones with varying uplift histories. The Indus Valley of Ladakh, northern India, runs northwestwards following the boundary between the relatively undeformed Ladakh Batholith to the north–east and the folded and thrusted Zanskar mountains to the south–west. In this region the Shyok Valley, on the northern side of the batholith, approximately parallels the course of the Indus. This study investigates geomorphic variations in transverse catchments that drain the Ladakh Batholith, into the Indus and Shyok rivers. The batholith has been divided into three zones based on varying structural characteristics of its northeastern and southwestern boundaries. Morphometric analysis of 62 catchments that drain into the Indus and Shyok valleys was carried out using three digital datasets, and supported by field observations. Morphometric asymmetry is evident in the central zone where the Shyok valley is considered tectonically inactive, but the Indus Valley is bound by the northeastwardly thrusting Indus Molasse and the batholith. In this zone the catchments that drain into the Indus Valley are more numerous, shorter, thinner and have lower hypsometric integrals than those that drain into the Shyok. By linking these observations with the regional geology and thermochronological data it is proposed that high sediment discharge from the deformed Indus Molasse Indus Valley has progressively raised base levels in the Indus Valley and resulted in sediment blanketing of the opposing tectonically quiescent catchments that drain southwestwards off the batholith. The Indus Molasse thrust front has propagated at least 36 km towards the Ladakh Batholith over the last 20 Ma. Hence it is proposed that this long term asymmetric structural deformation and exhumation has forced the Indus longitudinal valley laterally into the Ladakh Batholith resulting in the morphometric asymmetry of its transverse catchments. | ||||||
BibTeX:
@article{jamieson2004gm,
author = {Jamieson, Stewart S. R. and Sinclair, H.D. and Kirstein, L.A. and Purves, Ross S.},
title = {Tectonic forcing of longitudinal valleys in the {Himalaya}: morphological analysis of the {Ladakh Batholith}, {North India}.},
journal = {Geomorphology},
year = {2004},
volume = {58},
number = {1},
pages = {49-65},
doi = {doi:10.1016/S0169-555X(03)00185-5}
}
|
||||||
| Jamieson, S. S. R. & Sugden, D. E. | 2008 | Landscape evolution of Antarctica. [BibTeX] |
Antarctica: A Keystone in a Changing World - Proceedings of the 10th International Symposium on Antarctic Earth Sciences. The National Academies Press, Washington D.C. , 39-54 | ISM | ||
BibTeX:
@inproceedings{Jamieson2008Antarctica,
author = {Jamieson, Stewart S. R. and Sugden, David E.},
title = {Landscape evolution of {Antarctica}.},
booktitle = {Antarctica: A Keystone in a Changing World - Proceedings of the 10th International Symposium on Antarctic Earth Sciences.},
publisher = {The National Academies Press, Washington D.C.},
year = {2008},
pages = {39-54}
}
|
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| Jansson, P., Hock, R. & Schneider, T. | 2003 | The concept of glacier storage: a review. | Journal of Hydrology 282 , 116-129 | ISM | Glacier hydrology; Glacier storage; Water storage; review; | DOI |
| Abstract: Glacier storage is a widely used term, applied to different processes and time-scales by different disciplines in hydrology and glaciology. We identify that storage occurs as ice, snow, and water associated with three time-scales. Long-term storage concerns storage of ice and firn as glaciers on time-scales of years to centuries and longer. This storage affects global sea level and long-term water balance of glacierized catchments and is especially important for water resources in arid and semiarid areas. Intermediate-term storage is applicable to processes such as storage and release of snow and water, in and on a glacier on a seasonal scale. This is also the most common definition in the literature implied by the term storage. Intermediate-term storage affects runoff characteristics in glacierized catchments and downstream river flow regimes. Short-term storage concerns diurnal effects of drainage through the glacier including routing through snow, firn and en- and subglacial pathways. In addition to these time-scale dependent processes there are also event-driven storage releases, termed singular storage releases, including drainage from glacier surges and drainage of glacier-dammed water. These events are associated with glaciers but do not exhibit cyclic response or have irregular occurrences. It is evident that glacier storage is not handled well by current conceptual or mathematical models and that, e.g. sub- and englacial storage are poorly constrained. Hence, holistic approaches to studying and modelling glacier storage are of major importance to fully integrate glaciers into the hydrological balance to be used for water resources and river flow predictions on all time-scales. | ||||||
BibTeX:
@article{jansson2003jh,
author = {Jansson, Peter and Hock, Regine and Schneider, Thomas},
title = {The concept of glacier storage: a review.},
journal = {Journal of Hydrology},
year = {2003},
volume = {282},
pages = {116-129},
doi = {10.1016/S0022-1694(03)00258-0}
}
|
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| Jarvis, A., Reuter, H., Nelson, A. & Guevara, E. | 2006 | Void-filled seamless SRTM data V3, available from the CGIAR-CSI SRTM 90m Database: http://srtm.csi.cgiar.org [BibTeX] |
International Centre for Tropical Agriculture (CIAT) | URL |
||
BibTeX:
@manual{srtm2006,
author = {Jarvis, A. and Reuter, H.I. and Nelson, A. and Guevara, E.},
title = {Void-filled seamless {SRTM} data V3, available from the {CGIAR-CSI SRTM} 90m Database: http://srtm.csi.cgiar.org},
year = {2006},
url = {http://srtm.csi.cgiar.org}
}
|
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| Jarvis, A., Rubiano, J., Nelson, A., Farrow, A. & Mulligan, M. | 2004 | Practical use of SRTM data in the tropics: Comparisons with digital elevation models generated from cartographic data. [BibTeX] |
Working Document (198, 32 p.) International Centre for Tropical Agriculture (CIAT), Cali, Columbia | URL |
||
BibTeX:
@techreport{Jarvis2004,
author = {Jarvis, A. and Rubiano, J. and Nelson, A. and Farrow, A. and Mulligan, M.},
title = {Practical use of {SRTM} data in the tropics: Comparisons with digital elevation models generated from cartographic data.},
year = {2004},
number = {198, 32 p.},
url = {http://srtm.csi.cgiar.org/PDF/Jarvis4.pdf}
}
|
||||||
| Johnsen, S., Clausen, H. B., Dansgaard, W., Fuhrer, K., Gundestrup, N. Hammer, C. U., Iversen, P., Jouzel, J., Stauffer, B. & Steffensen, J. P. | 1992 | Irregular glacial interstadials recorded in a new Greenland ice core. | Nature 359 , 311-313 | ISM | DOI |
|
| Abstract: The Greenland ice sheet offers the most favourable conditions in the Northern Hemisphere for obtaining high-resolution continuous time series of climate-related parameters. Profiles of ^18O/<^16O ratio along three previous deep Greenland ice cores 1–3 seemed to reveal irregular but well-defined episodes of relatively mild climate conditions (interstadials) during the mid and late parts of the last glaciation, but there has been some doubt as to whether the shifts in oxygen isotope ratio were genuine representations of changes in climate, rather than artefacts due to disturbed stratification. Here we present results from a new deep ice core drilled at the summit of the Greenland ice sheet, where the depositional environ-ment and the flow pattern of the ice are close to ideal for core recovery and analysis. The results reproduce the previous findings to such a degree that the existence of the interstadial episodes can no longer be in doubt. According to a preliminary timescale based on stratigraphic studies, the interstadials lasted from 500 to 2,000 years, and their irregular occurrence suggests complexity in the behaviour of the North Atlantic ocean circulation. | ||||||
BibTeX:
@article{Johnsen1992Nature,
author = {Johnsen, S.J. and Clausen, H. B. and Dansgaard, W and Fuhrer, K. and Gundestrup, N. Hammer, C. U. and Iversen, P. and Jouzel, J. and Stauffer, B and Steffensen, J. P.},
title = {Irregular glacial interstadials recorded in a new Greenland ice core.},
journal = {Nature},
year = {1992},
volume = {359},
pages = {311-313},
doi = {10.1038/359311a0}
}
|
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| Johnson, J. | 2002 | Flow law derived velocity. [BibTeX] |
ISM | URL |
||
BibTeX:
@misc{johnson2002thesis,
author = {Johnson, Jesse},
title = {Flow law derived velocity.},
year = {2002},
url = {http://www.cs.umt.edu/u/johnson/research/phd_html/node10.html}
}
|
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| Jones, K. H. | 1998 | A comparison of algorithms used to compute hill slope as a property of the DEM. | Computers & Geoscience 24 (4) , 315-323 | slope; gradient; aspect; altitude; elevation; slope line; digital elevation model; ; complex numbers; | DOI |
|
| Abstract: The calculation of hill slope in the form of downhill gradient and aspect for a point in a digital elevation model (DEM), is a popular procedure in the hydrological, environmental and remote sensing. The most commonly used slope calculation algorithms employed on DEM topography data make use of a three by three search window, or kernel, centred on the grid point (grid cell) in question in order to calculate the gradient and aspect at that point. A comparison of eight frequently used slope calculation algorithms for digital elevation matrices has been carried out using both synthetic and real data as test surfaces. Morrison's surface III, a trigonometrically defined surface, was used as the synthetic test surface. This was differentiated analytically to give true gradient and aspect values against which to compare the results of the tested algorithms. The results of the best-performing slope algorithm on Morrison's surface were then used as the reference against which to compare the other tested algorithms on a real DEM. For both of the test surfaces residual gradient and aspect grids were calculated by subtracting the gradient and aspect grids produced by the algorithms on test from the true/reference gradient and aspect grids. The resulting residual gradient and aspect grids were used to calculate root-mean-square (RMS) residual error estimates that were used to rank the slope algorithms from "best" (lowest value of RMS residual error) to "worst" (largest value of RMS residual error). For Morrison's test surface, Fleming and Hoffer's method gave the "best" results for both gradient and aspect. Horn's method (used in ArcInfo GRID) also performed well for both gradient and aspect estimation. However, the popular maximum downward gradient method (MDG) performed poorly, coming last in the rankings. A similar pattern was seen in the gradient and aspect rankings derived using the Rhum DEM, with Horn's method performing well and the MDG method poorly. | ||||||
BibTeX:
@article{jones1998cg,
author = {Jones, Kevin H.},
title = {A comparison of algorithms used to compute hill slope as a property of the {DEM}.},
journal = {Computers \& Geoscience},
year = {1998},
volume = {24},
number = {4},
pages = {315-323},
doi = {10.1016/S0098-3004(98)00032-6}
}
|
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| Journel, A. G. | 1996 | Modelling uncertainty and spatial dependence: Stochastic imaging | International Journal of Geographical Information Science 10 (5) , 517-522 | uncertainty | uncertainty; | DOI |
| Abstract: The most vibrant area of research in geostatistics is stochastic imaging, that is, the modelling of spatial uncertainty through alternative, equiprobable, numerical representations (maps) of spatially distributed phenomena. These stochastic images are conditioned to a variety of data accounting for their specific measurement scale and reliability. Any geostatistical prediction is built on a prior model of spatial correlation that ties data to unsampled values and, equally importantly, unsampled values at different locations together. Since a major goal in the exercise of mapping is to display organization in space, spatial correlation is a necessity. As for uncertainty it is so pervasive that it is imperative to account for it. | ||||||
BibTeX:
@article{Journel1996IJGIS,
author = {Journel, Andre G.},
title = {Modelling uncertainty and spatial dependence: Stochastic imaging},
journal = {International Journal of Geographical Information Science},
year = {1996},
volume = {10},
number = {5},
pages = {517-522},
doi = {10.1080/026937996137846}
}
|
||||||
| Kaser, G., Juen, I., Georges, C., Gómez, J. & Tamayo, W. | 2003 | The impact of glaciers on the runoff and the reconstruction of mass balance history from hydrological data in the tropical Cordillera Blanca, Perú. | Journal of Hydrology 282 , 130-144 | Tropical glaciers; Climate change; Mountain hydrology; Tropical water resources | DOI |
|
| Abstract: A 41 years series of runoff and precipitation data from the Peruvian Cordillera Blanca demonstrates the high hygric seasonality in this tropical high mountain range. In this area, glaciers have a crucial impact on runoff which is of essential importance for the highly populated and cultivated valley of the Callejon de Huaylas particularly during the dry season. Whereas the mid latitudes glacier runoff amplifies the seasonal variation of runoff, the effect of glaciers in the low latitudes is a smoothing one. It decreases clearly with the decreasing degree of glaciation. In addition, particular circumstances of this tropical environment allow the reconstruction of a glacier mass balance history from the hydrological data for the second half of the 20th century. It shows a high synchronicity with the global trend of periods with glacier mass loss and gain. Comparison with length variations of three individual glaciers indicate a rather fast reaction of these glaciers to changes in mass balance. Although the mass balance variations show some differences among the individual catchment basins, the over all trend is uniform. A general positive correlation of mass balance variations with SOI is obvious but not regular. | ||||||
BibTeX:
@article{Kaser2003JHyd,
author = {Kaser, Georg and Juen, Irmgard and Georges, Christian and G{\'o}mez, Jes{\'u}s and Tamayo, William},
title = {The impact of glaciers on the runoff and the reconstruction of mass balance history from hydrological data in the tropical {Cordillera Blanca, Per{\'u}}.},
journal = {Journal of Hydrology},
year = {2003},
volume = {282},
pages = {130-144},
doi = {10.1016/S0022-1694(03)00259-2}
}
|
||||||
| Kaufmann, G., Wu, P. & Li, G. | 2000 | Glacial isostatic adjustment in Fennoscandia for a laterally heterogeneous earth. | Geophysical Journal International 143 , 262-273 | DOI |
||
| Abstract: Glaciation and deglaciation in Fennoscandia during the last glacial cycles has significantly perturbed the Earth's equilibrium figure. Changes in the Earth's solid and geoidal surfaces due to external and internal mass redistributions are recorded in sequences of ancient coastlines, now either submerged or uplifted, and are still visible in observations of present-day motions of the surface and glacially induced anomalies in the Earth's gravitational field. These observations become increasingly sophisticated with the availability of GPS measurements and new satellite gravity missions. Observational evidence of the mass changes is widely used to constrain the radial viscosity structure of the Earth's mantle. However, lateral changes in earth model properties are usually not taken into account, as most global models of glacial isostatic adjustment assume radial symmetry for the earth model. This simplifying assumption contrasts with seismological evidence of significant lateral variations in the Earth's crust and upper mantle throughout the Fennoscandian region. We compare predictions of glacial isostatic adjustment based on an ice model over the Fennoscandian region for the last glacial cycle for both radially symmetric and fully 3-D earth models. Our results clearly reveal the importance of lateral variations in lithospheric thickness and asthenospheric viscosity for glacially induced model predictions. Relative sea-level predictions can differ by up to 10–20 m, uplift rate predictions by 1–3 mm yr-1 and free-air gravity anomaly predictions by 2–4 mGal when a realistic 3-D earth structure as proposed by seismic modelling is taken into account. |
||||||
BibTeX:
@article{Kaufmann2000GJI,
author = {Kaufmann, Georg and Wu, Patrick and Li, Guoying},
title = {Glacial isostatic adjustment in Fennoscandia for a laterally heterogeneous earth.},
journal = {Geophysical Journal International},
year = {2000},
volume = {143},
pages = {262-273},
doi = {10.1046/j.1365-246x.2000.00247.x}
}
|
||||||
| Kerr, A. | 1993 | Topography, climate and ice masses: a review. | Terra Nova 5 (4) , 332-342 | ISM | DOI |
|
| Abstract: Topography acts as a filter between regional climate and the consequent response of a glacier or ice sheet. It influences the mass and energy inputs and modifies the ice dynamics. The evolution of the ice sheet surface and, over longer time scales, of the bed topography modulates the climatic forcing. Until we have a better understanding of these topographic linkages, the use of geophysical signals from former ice masses to determine palaeoclimates must be regarded as fundamentally flawed. | ||||||
BibTeX:
@article{Kerr1993TerraNova,
author = {Kerr, Andrew},
title = {Topography, climate and ice masses: a review.},
journal = {Terra Nova},
year = {1993},
volume = {5},
number = {4},
pages = {332-342},
doi = {10.1111/j.1365-3121.1993.tb00266.x}
}
|
||||||
| Kerr, A. | 1990 | The initiation of maritime ice sheets. [BibTeX] |
Zeitschrift für Gletscherkunde und Glazialgeologie 26 (1) , 69-79 | ISM | ||
BibTeX:
@article{kerr1990zgg,
author = {Kerr, A.},
title = {The initiation of maritime ice sheets.},
journal = {Zeitschrift f\"ur Gletscherkunde und Glazialgeologie},
year = {1990},
volume = {26},
number = {1},
pages = {69-79}
}
|
||||||
| Keuper, A. D. | 2004 | The influence of uncertainty metadata on decision-making using geographic data products. [BibTeX] |
Unpublished PhD thesis University of California, Santa Barbara | |||
BibTeX:
@phdthesis{Keuper2004phd,
author = {Keuper, Alex D.},
title = {The influence of uncertainty metadata on decision-making using geographic data products.},
school = {University of California, Santa Barbara},
year = {2004}
}
|
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| Kiamer, R. & Sjöberg, L. | 2005 | Effect of the SRTM global DEM on the determination of a high-resolution geoid model: a case study in Iran. | Journal of Geodesy 79 (9) , 540-551 | DEM | DEM ; SRTM; deviations; IRAN; uncertainty | DOI |
| Abstract: Any errors in digital elevation models (DEMs) will introduce errors directly in gravity anomalies and geoid models when used in interpolating Bouguer gravity anomalies. Errors are also propagated into the geoid model by the topographic and downward continuation (DWC) corrections in the application of StokesÂ’s formula. The effects of these errors are assessed by the evaluation of the absolute accuracy of nine independent DEMs for the Iran region. It is shown that the improvement in using the high-resolution Shuttle Radar Topography Mission (SRTM) data versus previously available DEMs in gridding of gravity anomalies, terrain corrections and DWC effects for the geoid model are significant. Based on the Iranian GPS/levelling network data, we estimate the absolute vertical accuracy of the SRTM in Iran to be 6.5 m, which is much better than the estimated global accuracy of the SRTM (say 16 m). Hence, this DEM has a comparable accuracy to a current photogrammetric high-resolution DEM of Iran under development. We also found very large differences between the GLOBE and SRTM models on the range of ?750 to 550 m. This difference causes an error in the range of ?160 to 140 mGal in interpolating surface gravity anomalies and ?60 to 60 mGal in simple Bouguer anomaly correction terms. In the view of geoid heights, we found large differences between the use of GLOBE and SRTM DEMs, in the range of ?1.1 to 1 m for the study area. The terrain correction of the geoid model at selected GPS/levelling points only differs by 3 cm for these two DEMs. | ||||||
BibTeX:
@article{Kiamer2005JGeod,
author = {Kiamer, R. and Sj\"oberg, L.E.},
title = {Effect of the {SRTM} global {DEM} on the determination of a high-resolution geoid model: a case study in Iran.},
journal = {Journal of Geodesy},
year = {2005},
volume = {79},
number = {9},
pages = {540-551},
doi = {10.1007/s00190-005-0006-8}
}
|
||||||
| Kienzle, S. | 2004 | The Effect of DEM Raster Resolution on First Order, Second Order and Compound Terrain Derivatives | Transactions in GIS 8 (1) , 83-111 | DEM | DEM; Resolution; Derivatives; Slope; Aspect; Terrain | DOI |
| Abstract: It is well known that the grid cell size of a raster digital elevation model has significant effects on derived terrain variables such as slope, aspect, plan and profile curvature or the wetness index. In this paper the quality of DEMs derived from the interpolation of photogrammetrically derived elevation points in Alberta, Canada, is tested. DEMs with grid cell sizes ranging from 100 to 5 m were interpolated from 100 m regularly spaced elevation points and numerous surface-specific point elevations using the ANUDEM interpolation method. In order to identify the grid resolution that matches the information content of the source data, three approaches were applied: density analysis of point elevations, an analysis of cumulative frequency distributions using the Kolmogorov-Smirnov test and the root mean square slope measure. Results reveal that the optimum grid cell size is between 5 and 20 m, depending on terrain complexity and terrain derivative. Terrain variables based on 100 m regularly sampled elevation points are compared to an independent high-resolution DEM used as a benchmark. Subsequent correlation analysis reveals that only elevation and local slope have a strong positive relationship while all other terrain derivatives are not represented realistically when derived from a coarse DEM. Calculations of root mean square errors and relative root mean square errors further quantify the quality of terrain derivatives. | ||||||
BibTeX:
@article{kienzle2004tigis,
author = {Kienzle, Stefan},
title = {The Effect of {DEM} Raster Resolution on First Order, Second Order and Compound Terrain Derivatives},
journal = {Transactions in GIS},
year = {2004},
volume = {8},
number = {1},
pages = {83-111},
doi = {10.1111/j.1467-9671.2004.00169.x}
}
|
||||||
| Kuhn, M. | 2003 | Redistribution of snow and glacier mass balance from a hydrometeorological model. | Journal of Hydrology 282 , 95-103 | ISM | basin; hydrometeorological; hydrology; | DOI |
| Abstract: This paper reports on the extension of a hydrometeorological model of glacierized basins to incorporate a detailed account of glacier mass balance. In this mass balance module a constant fraction of snow fall is redistributed within the basin from ice free areas to the glacier areas. In the particular basin discussed here solid precipitation on the glacier surface is increased by a factor of 2.15 over the basin mean of each 100 m altitude interval. The resulting mass balance parameters like mean annual specific balance, b(h), balance gradients, equilibrium line altitude and accumulation area ratio are within the range of records from other glaciers. The sensitivity of these quantities to meteorological input and model tuning parameters is evaluated, e.g. the sensitivity of mean specific mass balance to mean basin temperature is of the order of 800 mm/K. Emphasis is placed on the net accumulation outside the glacier areas in years with positive mass balance. | ||||||
BibTeX:
@article{kuhn2003jh,
author = {Kuhn, M.},
title = {Redistribution of snow and glacier mass balance from a hydrometeorological model.},
journal = {Journal of Hydrology},
year = {2003},
volume = {282},
pages = {95-103},
doi = {10.1016/S0022-1694(03)00256-7}
}
|
||||||
| Kumar, L., Skidmore, A. K. & Knowles, E. | 1997 | Modelling topographic variation in solar radiation in a GIS environment. | International Journal of Geographical Information Science 11 , 475-497 | DOI |
||
| Abstract: Clear sky shortwave solar radiation varies in response to altitude and elevation, surface gradient (slope) and orientation (aspect), as well as position relative to neighbouring surfaces. While the measurement of radiation flux on a relatively flat surface is straightforward, it requires a dense network of stations for mountainous terrain. The model presented here uses a digital elevation model to compute potential direct solar radiation and diffuse radiation over a large area, though the model may be modified to include parameters such as cloud cover and precipitable water content of the atmosphere. The purpose of this algorithm is for applied work in forestry, ecology, biology and agriculture where spatial variation of solar radiation is more important than calibrated values. The ability of the model to integrate radiation over long time periods in a computationally inexpensive manner enables it to be used for modelling radiation per se, for input into other hydrological, climatological or biological models. The model has been implemented for commercially available GIS (viz. Arc Info and Genasys) and is available over the Internet. |
||||||
BibTeX:
@article{Kumar1997ijgis,
author = {Kumar, Lalit and Skidmore, Andrew K. and Knowles, Edmund},
title = {Modelling topographic variation in solar radiation in a {GIS} environment.},
journal = {International Journal of Geographical Information Science},
year = {1997},
volume = {11},
pages = {475-497},
doi = {10.1080/136588197242266}
}
|
||||||
| Kyriakidis, P. C. | 2001 | Spatial Uncertainty in Ecology: Implications for Remote Sensing and GIS Applications. | Springer, Berlin | uncertainty | ||
| Abstract: This is the first book to take an ecological perspective on uncertainty in spatial data. It applies principles and techniques from geography and other disciplines to ecological research, bringing the tools of cartography, cognition, spatial statistics, remote sensing and computer sciences by way of spatial data. After describing the uses of such data in ecological research, the authors discuss how to account for the effects of uncertainty in various methods of analysis. | ||||||
BibTeX:
@inbook{Kyriakidis2001book,
author = {Kyriakidis, Phaedon C.},
title = {Spatial Uncertainty in Ecology: Implications for Remote Sensing and GIS Applications.},
publisher = {Springer, Berlin},
year = {2001}
}
|
||||||
| Kyriakidis, P. C. & Goodchild, M. F. | 2006 | On the prediction error variance of three common spatial interpolation schemes. | International Journal of Geographical Information Science 20 (8) , 823-855 | uncertainty, DEM | Spatial accuracy assessment; Error propagation; Linear interpolation; Bilinear interpolation; Geostatistics; Trend surface models | DOI |
| Abstract: Three forms of linear interpolation are routinely implemented in geographical information science, by interpolating between measurements made at the endpoints of a line, the vertices of a triangle, and the vertices of a rectangle (bilinear interpolation). Assuming the linear form of interpolation to be correct, we study the propagation of error when measurement error variances and covariances are known for the samples at the vertices of these geometric objects. We derive prediction error variances associated with interpolated values at generic points in the above objects, as well as expected (average) prediction error variances over random locations in these objects. We also place all the three variants of linear interpolation mentioned above within a geostatistical framework, and illustrate that they can be seen as particular cases of Universal Kriging (UK). We demonstrate that different definitions of measurement error in UK lead to different UK variants that, for particular expected profiles or surfaces (drift models), yield weights and predictions identical with the interpolation methods considered above, but produce fundamentally different (yet equally plausible from a pure data standpoint) prediction error variances. | ||||||
BibTeX:
@article{Kyriakidis2006IJGIS,
author = {Kyriakidis, Phaedon C. and Goodchild, Michael F.},
title = {On the prediction error variance of three common spatial interpolation schemes.},
journal = {International Journal of Geographical Information Science},
year = {2006},
volume = {20},
number = {8},
pages = {823-855},
doi = {10.1080/13658810600711279}
}
|
||||||
| Kyriakidis, P. C., Shortridge, A. & Goodchild, M. | 1999 | Geostatistics for conflation and accuracy assessment of digital elevation models. | International Journal of Geographical Information Science 13 (7) , 677-707 | uncertainty | ; ; ; geostatistics; accuracy assessment; | DOI |
| Abstract: A geostatistical methodology is proposed for integrating elevation estimates derived from digital elevation models (DEMs) and elevation measurements of higher accuracy, e.g., elevation spot heights. The sparse elevation measurements (hard data) and the abundant DEM-reported elevations (soft data) are employed formodeling the unknown higher accuracy (reference) elevation surface in a way that properly reflects the relative reliability of the two sources of information. Stochastic conditional simulation is performed for generating alternative, equiprobable images (numericalmodels) of the unknown reference elevation surface using both hard and soft data. These numerical models reproduce the hard elevation data at their measurement locations, and a set of auto and crosscovariancemodels quantifying spatial correlation between data of the two sources of information at various spatial scales. Fromthis set of alternative representations of the reference elevation, the probability that the unknown reference value is greater than that reported at each node in the DEMis determined. Joint uncertainty associated with spatial features observed in the DEM, e.g. the probability for an entire ridge existing, is also modeled from this set of alternative images. A case study illustrating the proposed conflation procedure is presented for a portion of a USGS one-degree DEM. It is suggested thatmaps of local probabilities for over or underestimation of the unknown reference elevation values from those reported in the DEM, and joint probability values attached to different spatial features, be provided to DEMusers in addition to traditionally reported summary statistics used to quantify DEM accuracy. Such a metadata element would be a valuable tool for subsequent decision-making processes that are based on the DEMelevation surface, or for targeting areas where more accurate elevation measurements are required. |
||||||
BibTeX:
@article{kyriakidis1999ijgis,
author = {Kyriakidis, Phaedon C. and Shortridge, Ashton and Goodchild, Michael},
title = {Geostatistics for conflation and accuracy assessment of digital elevation models.},
journal = {International Journal of Geographical Information Science},
year = {1999},
volume = {13},
number = {7},
pages = {677-707},
doi = {10.1080/136588199241067}
}
|
||||||
| Lambeck, K. & Nakiboglu, S. | 1980 | Seamount loading and stress in the ocean lithosphere. [BibTeX] |
Journal of Geophysical Research 85 , 6403-6418 | ISM | ||
BibTeX:
@article{Lambeck1980JGR,
author = {Lambeck, K. and Nakiboglu, S.M.},
title = {Seamount loading and stress in the ocean lithosphere.},
journal = {Journal of Geophysical Research},
year = {1980},
volume = {85},
pages = {6403-6418}
}
|
||||||
| Laube, P., van Kreveld, M. & Imfeld, S. | 2005 | Developments in Spatial Data Handling. | Springer, Berlin , 201-215 | Convergence - cluster detection - motion - moving point objects - pattern matching - proximity | DOI |
|
| Abstract: Technological advances in position aware devices increase the availability of tracking data of everyday objects such as animals, vehicles, people or football players. We propose a geographic data mining approach to detect generic aggregation patterns such as flocking behaviour and convergence in geospatial lifeline data. Our approach considers the object’s motion properties in an analytical space as well as spatial constraints of the object’s lifelines in geographic space. We discuss the geometric properties of the formalised patterns with respect to their efficient computation. | ||||||
BibTeX:
@inbook{Laube2005inbook,
author = {Laube, Patrick and van Kreveld, Marc and Imfeld, Stephan},
title = {Developments in Spatial Data Handling.},
publisher = {Springer, Berlin},
year = {2005},
pages = {201-215},
doi = {10.1007/3-540-26772-7_16}
}
|
||||||
| Le Brocq, A. M., Payne, A. J. & Siegert, M. J. | 2006 | West Antarctic balance calculations: Impact of flux-routing algorithm, smoothing algorithm and topography. | Computers & Geoscience 32 (10) , 1780-1795 | ISM | DOI |
|
| Abstract: Balance flux and velocity calculations are important in understanding the large-scale dynamics of ice masses and their state of balance. However the grid-based (finite difference) nature of the current algorithms means that there is a variety of ways in which the balance flux and velocity can be calculated. The flux-routing algorithm, grid orientation and grid size all have an impact on the balance calculations. Previous work has relied on the assumption that the ice flow direction is orthogonal to the surface contours, with the surface having been smoothed to incorporate a representation of the longitudinal stresses within the ice. This assumption is a simplification of the gravitational driving stress equation, which relates the driving stress to the gradient of the surface slope and the ice thickness. Further, the common representation of longitudinal stresses using a fixed size smoothing filter is a simplification of the theoretical treatment of longitudinal stresses by Kamb, B., Echelmeyer, K.A. [1986. Stress–gradient coupling in glacier flow: 1. longitudinal averaging of the influence of ice thickness and surface slope. Journal of Glaciology 32 (111), 267–298]. This study investigates the sensitivity of the balance calculations to these issues, using the West Antarctic Ice Sheet as a case study. Significant differences in both ice stream margins and values of ice flux within them result from the algorithm choice, gridorientation and gridsize. The inclusion of a theoretically appropriate smoothing approach improves the coherence of the pattern of ice flow. The incorporation of gravitational driving stress has a small effect in comparison to practical issues such as the grid orientation and size. As higher resolution datasets (less than 5 km) become available for many ice masses, there is a temptation to calculate the balance flux using the same algorithms on the finer grids. The results shown in this study suggest that the type of algorithm most commonly used is not suitable for these finer grids. The impact of the practical issues described here encourages caution in the use of grid-based balance distributions and values, especially when considering the state of balance of individual ice streams. | ||||||
BibTeX:
@article{LeBroq2006CG,
author = {{Le Brocq}, Anne M. and Payne, Anthony J. and Siegert, Martin J.},
title = {{West Antarctic} balance calculations: Impact of flux-routing algorithm, smoothing algorithm and topography.},
journal = {Computers \& Geoscience},
year = {2006},
volume = {32},
number = {10},
pages = {1780-1795},
doi = {10.1016/j.cageo.2006.05.003}
}
|
||||||
| Lee, J. | 1996 | Digital Elevation Models: Issues of Data Accuracy and Applications. | Proceedings of the 1996 ESRI International User Conference | DEM | URL |
|
| Abstract: With the increasing availability of data for digital elevation models (DEM) and the software capable of processing them, it is important for users of DEM data to be aware of the effect that data accuracy has on the results of their applications. In this paper, we examined the relationship between simulated errors and the results of extracting hydrological features from DEMs. The simulated errors were controlled to have various degrees of spatial clusterness to allow further investigation of the impact on the extracted hydrological features. The results of our study suggest that even errors of small magnitudes would significantly affect the quality of extracted hydrological features. It is extremely important for users of DEM data to recognize this limitation and not to overly confident on the results of less accurate data. |
||||||
BibTeX:
@inproceedings{Lee1996esri,
author = {Lee, Jay},
title = {Digital Elevation Models: Issues of Data Accuracy and Applications.},
booktitle = {Proceedings of the 1996 ESRI International User Conference},
year = {1996},
url = {http://gis.esri.com/library/userconf/proc96/TO150/PAP145/P145.HTM}
}
|
||||||
| Lee, J., Snyder, P. K. & Fisher, P. F. | 1992 | Modeling the effect of data errors on feature extraction from digital elevation models. [BibTeX] |
American Society for Photogrammetry and Remote Sensing Photogrammetric Engineering and Remote Sensing 58 (10) , 1461-1467 | DEM | URL |
|
BibTeX:
@article{lee1992pers,
author = {Lee, Jay and Snyder, Peter K. and Fisher, Peter F.},
title = {Modeling the effect of data errors on feature extraction from digital elevation models.},
journal = {Photogrammetric Engineering and Remote Sensing},
publisher = {American Society for Photogrammetry and Remote Sensing},
year = {1992},
volume = {58},
number = {10},
pages = {1461-1467},
url = {http://gis.geog.kent.edu/People/LeePapers/FeatureExtraction.pdf}
}
|
||||||
| Lefebre, F., Gallée, H., van Ypersele, J. & Greuell, W. | 2003 | Modeling of snow and ice melt at ETH Camp (West Greenland): A study of surface albedo. | Journal of Geophysical Research 108 (D8, 4231) | modeling surface albedo; Greenland; mass balance; | DOI |
|
| Abstract: The objective of this paper is to present the validation over Greenland of a thermodynamic snow-ice model that was complemented with the snow metamorphism and albedo parameterizations of the Centre d’Etudes de la Neige (Grenoble, France) in order to make the surface albedo variable and interactive. Special attention is given to the surface albedo since it is the most important parameter in energy exchanges with the atmosphere for snow and ice melt. The development of an integrated (snow, ice, and water) albedo model takes into account the different surface types observed on an ice sheet, and the snow albedo is calculated from the simulated surface snow grains. The validation for a polar site has been done at ETH Camp (West Greenland, 1155 m above sea level) during the 1990 and 1991 summer seasons. Although both ablation seasons differed greatly (in 1990 it showed a negative mass balance while in 1991 it ended with a positive mass balance), a single model configuration was able to provide good results for both 1990 and 1991. These simulations show that the snow metamorphism laws included enable an accurate simulation of the surface albedo and henceforth of the surface mass balance for a polar site, provided that the snow model is correctly forced at its surface level and that meltwater retention, percolation, and drainage are well represented in the snow model. The model results are also compared with two other modeling approaches, and differences between the three snow models are detailed. |
||||||
BibTeX:
@article{Lefebre2003JGR,
author = {Lefebre, F. and Gall{\'e}e, H. and van Ypersele, J.-P. and Greuell, W.},
title = {Modeling of snow and ice melt at {ETH} Camp {(West Greenland)}: A study of surface albedo.},
journal = {Journal of Geophysical Research},
year = {2003},
volume = {108},
number = {D8, 4231},
doi = {10.1029/2001JD001160}
}
|
||||||
| Letréguilly, A., Huybrechts, P. & Reeh, N. | 1991 | Steady-state characteristics of the Greenland ice sheet under different climates. | Journal of Glaciology 37 , 149-157 | |||
| Abstract: The Greenland ice sheet is modelled to simulate its extent and volume in warmer climates, and also to find out whether the ice sheet would re-form on the ice-free bedrock under present climatic conditions. The ice sheet model is a three-dimensional thermo-mechanical model with a fine resolution grid. The bedrock surface beneath the ice sheet was mapped using radio-echo-sounding measurements by the Electromagnetic Institute, Copenhagen. The model experiments show that increased temperature will result in ice-margin retreat, but the ice sheet is relatively stable; it takes a rather high temperature rise of at least 6¡C for the ice sheet to disappear completely, which indicates that the ice sheet probably survived the last interglacial. Also, it appears that the Greenland ice sheet is not a mere relict ice mass from a previously colder climate but that the ice sheet will still re-form on the bare bedrock under the present, or even slightly warmer, climatic conditions. | ||||||
BibTeX:
@article{Letreguilly1991JGla,
author = {Letr{\'e}guilly, Anne and Huybrechts, Philippe and Reeh, Niels},
title = {Steady-state characteristics of the {Greenland} ice sheet under different climates.},
journal = {Journal of Glaciology},
year = {1991},
volume = {37},
pages = {149-157}
}
|
||||||
| Letréguilly, A., Reeh, N. & Huybrechts, P. | 1991 | The Greenland ice sheet through the last glacial-interglacial cycle. | Global and Planetary Change 4 (4) , 385-394 | |||
| Abstract: The evolution of the Greenland ice sheet during the last 150,000 years, in response to a climate history derived from a Greenland ice-margin oxygen-18 record, is simulated by means of a three-dimensional, time-dependent ice-sheet model. The calculations indicate that the ice sheet displayed considerable thinning and ice-margin retreat during the last interglacial (the Eemian) and during a warm interstadial c. 100,000 yr B.P., resulting in splitting up of the ice sheet into a central-northern and a southern part. However, the ice sheet in Central Greenland survived the warm stages with almost unchanged surface elevations as compared with the present. | ||||||
BibTeX:
@article{Letreguilly1991GPC,
author = {Letr{\'e}guilly, Anne and Reeh, Niels and Huybrechts, Philippe},
title = {The Greenland ice sheet through the last glacial-interglacial cycle.},
journal = {Global and Planetary Change},
year = {1991},
volume = {4},
number = {4},
pages = {385-394}
}
|
||||||
| Leung, L. & Ghan, S. | 1998 | Parameterizing Subgrid Orographic Precipitation and Surface Cover in Climate Models | Monthly Weather Review 126 , 3271-321 | Subgrids | ||
| Abstract: Previous development of the Pacific Northwest National Laboratory’s regional climate model has focused on representing orographic precipitation using a subgrid parameterization where subgrid variations of surface elevation are aggregated to a limited number of elevation classes. An airflow model and a thermodynamic model are used to parameterize the orographic uplift/descent as air parcels cross over mountain barriers or valleys. This paper describes further testing and evaluation of this subgrid parameterization. Building upon this modeling framework, a subgrid vegetation scheme has been developed based on statistical relationships between surface elevation and vegetation. By analyzing high-resolution elevation and vegetation data, a dominant land cover is defined for each elevation band of each model grid cell to account for the subgrid heterogeneity in vegetation. When larger lakes are present, they are distinguished from land within elevation bands and a lake model is used to simulate the thermodynamic properties. The use of the high-resolution vegetation data and the subgrid vegetation scheme has resulted in an improvement in the model’s representation of surface cover over the western United States. Simulation using the new vegetation scheme yields a 18C cooling when compared with a simulation where vegetation was derived from a 30-min global vegetation dataset without subgrid vegetation treatment; this cooling helps to reduce the warm bias previously found in the regional climate model. A 3-yr simulation with the subgrid parameterization in the climate model is compared with observations. | ||||||
BibTeX:
@article{Leung1998MWR,
author = {Leung, L.R. and Ghan, S.J.},
title = {Parameterizing Subgrid Orographic Precipitation and Surface Cover in Climate Models},
journal = {Monthly Weather Review},
year = {1998},
volume = {126},
pages = {3271-321}
}
|
||||||
| Leung, L. R., Wigmosta, M. S., Ghan, S. J., Epstein, D. J. & Vail, L. W. | 1996 | Application of a subgrid orographic precipitation/surface hydrology scheme to a mountain watershed | Journal of Geophysical Research 101 (D8) , 12803-12818 | DOI URL |
||
| Abstract: A regional climate model including a physically based parameterization of the subgrid effects of topography on clouds and precipitation is driven by observed meteorology on its lateral boundaries for a period of 12 months. The meteorology simulated by the model for each subgrid elevation class is distributed across a mountain watershed according to the surface elevation within the watershed. The simulated meteorology is used to drive a detailed model of hydrology-vegetation dynamics at the topographic scale described by digital elevation data, 180 m. The watershed model, which includes a two-layer canopy model for evapotranspiration, an energy-balance model for snow accumulation and melt, a two-layer rooting zone model, and a quasi-three-dimensional saturated subsurface flow model, is used to simulate the seasonal cycle of the accumulation and melt of snow and the accumulation and discharge of surface water within a mountain watershed in northwestern Montana. Comparisons between the simulated and the recorded snow cover and river discharge at the base of the watershed indicate comparable if not better agreement than between the recorded fields and those simulated by the watershed model driven by meteorolgy observed at two stations within the watershed. The agreement with the recorded discharge, precipitation, and snow water equivalent is also clearly superior to simulations driven by the regional climate model run without the subgrid parameterization but with one-third the grid size of the simulation with the subgrid parameterization | ||||||
BibTeX:
@article{Leung1996JGR,
author = {{Leung}, L.~R. and {Wigmosta}, M.~S. and {Ghan}, S.~J. and {Epstein}, D.~J. and {Vail}, L.~W.},
title = {Application of a subgrid orographic precipitation/surface hydrology scheme to a mountain watershed},
journal = {Journal of Geophysical Research},
year = {1996},
volume = {101},
number = {D8},
pages = {12803-12818},
url = {http://www.agu.org/pubs/crossref/1996/96JD00441.shtml},
doi = {10.1029/96JD00441}
}
|
||||||
| Li, Z., Zhu, Q. & Gold, C. | 2005 | Digital Terrain Modelling: Principles and Methodology [BibTeX] |
CRC Press, Boca Raton | GIS, DEM | ||
BibTeX:
@book{Li2005book,
author = {Li, Zhilin and Zhu, Qing and Gold, Christopher},
title = {Digital Terrain Modelling: Principles and Methodology},
publisher = {CRC Press, Boca Raton},
year = {2005}
}
|
||||||
| Lindsay, J. B. | 2006 | Sensitivity of channel mapping techniques to uncertainty in digital elevation data. | International Journal of Geographical Information Science 20 (6) , 669-692 | DEM | DOI |
|
| Abstract: Digital elevation data are now commonly used to map channel networks automatically. This paper evaluates the sensitivity of six methods of extracting channel networks from digital elevation models (DEMs) to elevation error. As such, the robustness of channel mapping techniques against noisy data was evaluated and not the accuracy of DEM extracted channel networks. Stochastic simulations were used in combination with a fine resolution LiDAR DEM of a small upland catchment to assess the robustness of each of the channel mapping algorithms. Findings showed that the four tested methods that were based on identifying patterns or positions in the surface morphology were more sensitive to elevation error than the two methods that were based on simulating overland flow and channelization processes, particularly at lower error magnitudes. While the morphology based channel mapping methods were highly sensitive to the degree of spatial autocorrelation in elevation error fields, the channelization based methods were relatively insensitive. Drainage network extent and the geometry of exterior stream channels were both found to be greatly influenced by low to moderate degrees of topographic error. Although LiDAR data were found to provide a sufficient resolution for mapping fine scale headwater channels, the greater surface roughness did present challenges for automated channel mapping techniques. | ||||||
BibTeX:
@article{Lindsay2006IJGIS,
author = {Lindsay, John B.},
title = {Sensitivity of channel mapping techniques to uncertainty in digital elevation data.},
journal = {International Journal of Geographical Information Science},
year = {2006},
volume = {20},
number = {6},
pages = {669-692},
doi = {10.1080/13658810600661433}
}
|
||||||
| Liston, G. E. | 2004 | Representing Subgrid Snow Cover Heterogeneities in Regional and Global Models. | Journal of Climate 17 (6) , 1381-1397 | Subgrids | DOI |
|
| Abstract: To improve the depiction of autumn through spring land-atmosphere interactions and feedbacks within regional and global weather, climate, and hydrologic models, a Subgrid SNOW Distribution (SSNOWD) submodel that explicitly includes subgrid snow-depth and snow-cover variability has been developed. From both atmospheric and hydrologic perspectives, the subgrid snow-depth distribution is an important quantity to account for within large-scale models. In the natural system, these subgrid snow-depth distributions are largely responsible for the mosaic of snow-covered and snow-free areas that develop as the snow melts, and the impacts of these fractional areas must be quantified in order to realistically simulate grid-averaged surface fluxes. SSNOWD's formulation incorporates observational studies showing that snow distributions can be described by a lognormal distribution and the snow-depth coefficient of variation. Using an understanding of the physical processes that lead to these observed snow-depth variations, a global distribution of nine subgrid snow-depth-variability categories was developed, and coefficient-of-variation values were assigned to each category based on published measurements. In addition, SSNOWD adopts the physically realistic approach of performing separate surface-energy-balance calculations over the snow-covered and snow-free portions of each model grid cell and weighing the resulting fluxes according to these fractional areas. Using a climate version of the Regional Atmospheric Modeling System (ClimRAMS) over a North American domain, SSNOWD was compared with a snow-cover formulation similar to those currently used in most general circulation models. The simulations indicated that accounting for snow-distribution variability has a significant impact on snow-cover evolution and associated energy and moisture fluxes. | ||||||
BibTeX:
@article{Liston2004JC,
author = {Liston, Glen E.},
title = {Representing Subgrid Snow Cover Heterogeneities in Regional and Global Models.},
journal = {Journal of Climate},
year = {2004},
volume = {17},
number = {6},
pages = {1381-1397},
doi = {10.1175/1520-0442(2004)017<1381:RSSCHI>2.0.CO;2}
}
|
||||||
| Liu, H. & Jezek, K. C. | 1999 | Investigating DEM error patterns by directional variograms and Fourier analysis. | Geographical Analysis 31 , 249-266 | DEM | DEM; error modelling; variogramms; fft; fourier analysis; error pattern | URL |
| Abstract: In many spatial analyses and GIS applications, a Digital Elevation Model (DEM) is often used to derive a uariety of new cariables and parameters. Previous research shows that the accuracy of derived variables is affected, not merely by the magnitude of DEM error and the algorithms applied to derive these variables, but also by the spatial structure of DEM errors. However, the lack of knowledge and understanding of the spatial structure of DEM errors often handicaps the analysis of error propagation. This paper investigates the spatial autocorrelation and anisotropic pattern of DEM error by using directional variograms in the spatial domain and Fourier analysis in the frequency domain. Based on an empirical study, it is concluded that the spatial autocorrelation pattern of DEM errors is anisotropic and scaledependent, and that the maximum direction and range of the autocorrelation depends upon the orientation and wavelength of the terrain features. For a smooth terrain, the magnitude of DEM errors is correlated to surface slope. For a rugged terrain, the elevation values in DEMs tend to be underestimated in ridges, and overestimated in valleys, but the correlation between the DEM error and surface slope is quite low. | ||||||
BibTeX:
@article{Liu1999GAnalys,
author = {Liu, Hongxing and Jezek, Kenneth C.},
title = {Investigating {DEM} error patterns by directional variograms and Fourier analysis.},
journal = {Geographical Analysis},
year = {1999},
volume = {31},
pages = {249-266},
url = {http://geog.tamu.edu/%7Eliu/publications/error_fourier.pdf}
}
|
||||||
| Liu, H., Jezek, K. C. & Li, B. | 1999 | Development of an Antarctic digital elevation model by integrating cartographic and remotely sensed data: A geographic information system based approach. | Journal of Geophysical Research 104 (23) , 23199-23214 | DOI URL |
||
| Abstract: We present a high-resolution digital elevation model (DEM) of the Antarctic. It was created in a geographic information system (GIS) environment by integrating the best available topographic data from a variety of sources. Extensive GIS-based error detection and correction operations ensured that our DEM is free of gross errors. The carefully designed interpolation algorithms for different types of source data and incorporation of surface morphologic information preserved and enhanced the fine surface structures present in the source data. The effective control of adverse edge effects and the use of the Hermite blending weight function in data merging minimized the discontinuities between different types of data, leading to a seamless and topographically consistent DEM throughout the Antarctic. This new DEM provides exceptional topographical details and represents a substantial improvement in horizontal resolution and vertical accuracy over the earlier, continental-scale renditions, particularly in mountainous and coastal regions. It has a horizontal resolution of 200 m over the rugged mountains, 400 m in the coastal regions, and approximately 5 km in the interior. The vertical accuracy of the DEM is estimated at about 100–130 m over the rugged mountainous area, better than 2 m for the ice shelves, better than 15 m for the interior ice sheet, and about 35 m for the steeper ice sheet perimeter. The Antarctic DEM can be obtained from the authors. | ||||||
BibTeX:
@article{Liu1999JGR,
author = {Liu, Hongxing and Jezek, Kenneth C. and Li, B.},
title = {Development of an Antarctic digital elevation model by integrating cartographic and remotely sensed data: A geographic information system based approach.},
journal = {Journal of Geophysical Research},
year = {1999},
volume = {104},
number = {23},
pages = {23199-23214},
url = {http://www.agu.org/pubs/crossref/1999/1999JB900224.shtml},
doi = {10.1029/1999JB900224}
}
|
||||||
| Longley, P. A., Goodchild, M. F., Maguire, D. J. & Rhind, D. R. | 2005 | Geographic Information Systems and Science. [BibTeX] |
John Wiley & Sons, Inc., Chichester | GIS | ||
BibTeX:
@book{Longley2005book,
author = {Longley, Paul A. and Goodchild, Michael F. and Maguire, David J. and Rhind, David R.},
title = {Geographic Information Systems and Science.},
publisher = {John Wiley \& Sons, Inc., Chichester},
year = {2005}
}
|
||||||
| Luce, C. H. & Tarboton, D. G. | 2001 | Modeling Snowmelt Over an Area: Modeling Subgrid Scale Heterogeneity in Distributed Model Elements. | Proc. MODSIM | Subgrids | ||
| Abstract: We analyze the parameterization of sub-grid scale variability in snow accumulation and melt models from a physical perspective considering the causes of the variability and the effect on snowpack energy exchange. The source of temporal changes in spatial variance of snow water equivalent is the covariance between snow water equivalent and the accumulation or melt rate at each point. Variability caused by drifting and differential solar radiation can be effectively parameterized with areal depletion curves relating snow covered area to basin average snow water equivalent. As a first approximation, depletion curves may be estimated from the distribution of snow at peak accumulation. Improvements can be made to the depletion curve by using the joint distribution of solar radiation and snow water equivalent at peak accumulation. Consideration of how distributions may change as the model element size increases provides insight into how this conceptualization may be applied to scaling up snowmelt models. | ||||||
BibTeX:
@inproceedings{Luce2001MODSIM,
author = {Luce, Charles H. and Tarboton, David G.},
title = {Modeling Snowmelt Over an Area: Modeling Subgrid Scale Heterogeneity in Distributed Model Elements.},
booktitle = {Proc. MODSIM},
year = {2001}
}
|
||||||
| Luce, C. H., Tarboton, D. G. & Cooley, K. R. | 1999 | Sub-grid parameterization of snow distribution for an energy and mass balance snow cover model. | Hydrological Processes 13 , 1921-1933 | Subgrid | sub-grid parameterization; snow distribution; snow water equivalence; energy balance model | URL |
| Abstract: Representation of sub-element scale variability in snow accumulation and ablation is increasingly recognized as important in distributed hydrologic modelling. Representing sub-grid scale variability may be accomplished through numerical integration of a nested grid or through a lumped modelling approach. We present a physically based model of the lumped snowpack mass and energy balance applied to a 26-ha rangeland catchment with high spatial variability in snow accumulation and melt. Model state variables are snow-covered area average snow energy content (U), the basin-average snow water equivalence (Wa), and snow-covered area fraction (Af). The energy state variable is evolved through an energy balance. The snow water equivalence state variable is evolved through a mass balance, and the area state variable is updated according to an empirically derived relationship, Af(Wa), that is similar in nature to depletion curves used in existing empirical basin snowmelt models. As snow accumulates, the snow covered area increases rapidly. As the snowpack ablates, Af decreases as Wa decreases. This paper shows how the relationship Af(Wa) for the melt season can be estimated from the distribution of snow water equivalence at peak accumulation in the area being modelled. We show that the depletion curve estimated from the snow distribution of peak accumulation at the Upper Sheep Creek sub-basin of Reynolds Creek Experimental Watershed compares well against the observed depletion data as well as modelled depletion data from an explicit spatially distributed energy balance model. Comparisons of basin average snow water equivalence between the lumped model and spatially distributed model show good agreement. Comparisons to observed snow water equivalence show poorer but still reasonable agreement. The sub-grid parameterization is easily portable to other physically based point snowmelt models. It has potential application for use in hydrologic and climate models covering large areas with large model elements, where a computationally inexpensive parameterization of sub-grid snow processes may be important | ||||||
BibTeX:
@article{Luce1999HP,
author = {Luce, Charles H. and Tarboton, David G. and Cooley, Keith R.},
title = {Sub-grid parameterization of snow distribution for an energy and mass balance snow cover model.},
journal = {Hydrological Processes},
year = {1999},
volume = {13},
pages = {1921-1933},
url = {http://www3.interscience.wiley.com/cgi-bin/abstract/64500506/ABSTRACT}
}
|
||||||
| Lunt, D. J., Valdes, P. J., Haywood, A. & Rutt, I. C. | 2008 | Closure of the Panama Seaway during the Pliocene: implications for climate and Northern Hemisphere glaciation. | Climate Dynamics 30 (1) , 1-18 | ISM | DOI |
|
| Abstract: The “Panama Hypothesis” states that the gradual closure of the Panama Seaway, between 13 million years ago (13 Ma) and 2.6 Ma, led to decreased mixing of Atlantic and Pacific water Masses, the formation of North Atlantic Deep water and strengthening of the Atlantic thermohaline circulation, increased temperatures and evaporation in the North Atlantic, increased precipitation in Northern Hemisphere (NH) high latitudes, culminating in the intensification of Northern Hemisphere Glaciation (NHG) during the Pliocene, 3.2–2.7 Ma. Here we test this hypothesis using a fully coupled, fully dynamic ocean-atmosphere general circulation model (GCM) with boundary conditions specific to the Pliocene, and a high resolution dynamic ice sheet model. We carry out two GCM simulations with “closed” and “open” Panama Seaways, and use the simulated climatologies to force the ice sheet model. We find that the models support the “Panama Hypothesis” in as much as the closure of the seaway results in a more intense Atlantic thermohaline circulation, enhanced precipitation over Greenland and North America, and ultimately larger ice sheets. However, the volume difference between the ice sheets in the “closed” and “open” configurations is small, equivalent to about 5 cm of sea level. We conclude that although the closure of the Panama Seaway may have slightly enhanced or advanced the onset of NHG, it was not a major forcing mechanism. Future work must fully couple the ice sheet model and GCM, and investigate the role of orbital and CO2 effects in controlling NHG. | ||||||
BibTeX:
@article{Lunt2008CD,
author = {Lunt, Daniel J. and Valdes, Paul J. and Haywood, Alan and Rutt, Ian C.},
title = {{Closure of the Panama Seaway during the Pliocene: implications for climate and Northern Hemisphere glaciation.}},
journal = {Climate Dynamics},
year = {2008},
volume = {30},
number = {1},
pages = {1-18},
doi = {10.1007/s00382-007-0265-6}
}
|
||||||
| Lythe, M., Vaughan, D. G. & BEDMAP-Consortium | 2001 | BEDMAP: A new ice thickness and subglacial topographic model of Antarctica. | Journal of Geophysical Research 106 (B6) , 11335-11352 | ISM | BEDMAP; ; ice thickness | DOI URL |
| Abstract: Measurements of ice thickness on the Antarctic ice sheet collected during surveys undertaken over the past 50 years have been brought together into a single database. From these data, a seamless suite of digital topographic models have been compiled for Antarctica and its surrounding ocean. This includes grids of ice sheet thickness over the grounded ice sheet and ice shelves, water column thickness beneath the floating ice shelves, bed elevation beneath the grounded ice sheet, and bathymetry to 60?°S, including the sub-ice-shelf cavities. These grids are consistent with a recent high-resolution surface elevation model of Antarctica. While the digital models have a nominal spatial resolution of 5 km, such high resolution is justified by the original data density only over a few parts of the ice sheet. The suite does, however, provide an unparalleled vision of the geosphere beneath the ice sheet and a more reliable basis for ice sheet modeling than earlier maps. The total volume of the Antarctic ice sheet calculated from the BEDMAP grid is 25.4 million km3, and the total sea level equivalent, derived from the amount of ice contained within the grounded ice sheet, is 57 m, comprising 52 m from the East Antarctic ice sheet and 5 m from the West Antarctic ice sheet, slightly less than earlier estimates. The gridded data sets can be obtained from the authors. | ||||||
BibTeX:
@article{Lythe2001JGR,
author = {Lythe, M.B. and Vaughan, D. G. and {BEDMAP-Consortium}},
title = {{BEDMAP}: A new ice thickness and subglacial topographic model of Antarctica.},
journal = {Journal of Geophysical Research},
year = {2001},
volume = {106},
number = {B6},
pages = {11335-11352},
url = {http://www.agu.org/journals/jb/jb0106/2000JB900449/pdf/2000JB900449.pdf},
doi = {10.1029/2000JB900449}
}
|
||||||
| Lythe, M., Vaughan, D. G. & BEDMAPConsortium | 2000 | BEDMAP - bed topography of the Antarctic, 1:10 000 000 scale map. [BibTeX] |
British Antarctic Survey | DEM; ISM | data | |
BibTeX:
@manual{lythe2000bedmap,
author = {Lythe, M.B. and Vaughan, D. G. and BEDMAPConsortium},
title = {BEDMAP - bed topography of the Antarctic, 1:10 000 000 scale map.},
year = {2000},
edition = {BAS (Misc) 9}
}
|
||||||
| López, C. | 2000 | Improving the Elevation Accuracy of Digital Elevation Models: A Comparison of Some Error Detection Procedures. | Transactions in GIS 4 (1) , 43-64 | DEM | DOI |
|
| Abstract: The widespread availability of powerful desktop computers, easy-to-use software tools and geographic datasets have raised the quality problem of input data to be a crucial one. Even though accuracy has been a concern in every serious application, there are no general tools for its improvement. Some particular ones exist, however, and some results are presented here for a particular case of quantitative raster data: Digital Elevation Models (DEM). Two procedures designed to detect anomalous values (also named gross errors, outliers or blunders) in DEMs, but valid also for other quantitative raster datasets, were tested. A DEM with elevations varying from 181 to 1044 m derived from SPOT data has been used as a contaminated sample, while a manually derived DEM obtained from aerial photogrammetry was regarded as the ground truth to allow a direct performance comparison for the methods with real errors. It is assumed that a "better" value can be measured or obtained through some methodology once an outlier location is suggested. The options are different depending upon the user (DEM producers might go to the original data and make another reading, while end users might use interpolation). Both choices were considered in this experiment. Preliminary results show that for the available dataset, the accuracy might be improved to some extent with very little effort. Effort is defined here as the percentage of points suggested by the methodology in relation with its total number: thus 100 per cent effort implies that all points have been checked. The method proposed by López (1997) gave poor results, because it has been designed for errors with low spatial autocorrelation (which is not the case here). A modified version was then designed and compared with the method proposed by FelicÃsimo (1994). The three procedures can be applied both for error detection during DEM generation and by end users, and they might be of use for other quantitative raster data. The choice of the best methodology is different depending on the effort involved. The conclusions have been derived for a photogrammetrically obtained DEM; other production procedures might lead to different results. | ||||||
BibTeX:
@article{Lopez2000TIGIS,
author = {L{\'o}pez, Carlos},
title = {Improving the Elevation Accuracy of Digital Elevation Models: A Comparison of Some Error Detection Procedures.},
journal = {Transactions in GIS},
year = {2000},
volume = {4},
number = {1},
pages = {43-64},
doi = {10.1111/1467-9671.00037}
}
|
||||||
| MacEachren, A. M., Robinson, A., Hopper, S., Gardner, S., Murray, R., Gahegan, M. & Hetzler, E. | 2005 | Visualizing Geospatial Information Uncertainty: What We Know and What We Need to Know. [BibTeX] |
Cartography and Geographic Information Science 32 (3) , 139-160 | DEM, GIS | DOI |
|
BibTeX:
@article{MacEachren2005CartGISc,
author = {MacEachren, Alan M. and Robinson, Anthony and Hopper, Susan and Gardner, Steven and Murray, Robert and Gahegan, Mark and Hetzler, Elisabeth},
title = {Visualizing Geospatial Information Uncertainty: What We Know and What We Need to Know.},
journal = {Cartography and Geographic Information Science},
year = {2005},
volume = {32},
number = {3},
pages = {139-160},
doi = {10.1559/1523040054738936}
}
|
||||||
| MacMillan, R. A., McNabb, D. H. & Jones, R. K. | 2000 | Automated landform classification using DEMs: a conceptual framework for a multi-level, hierarchy of hydrologically and geomorphologicaly oriented physiographic mapping units | 4th International Conference on GIS and Environmental Modeling (GIS/EM4). Problems, Prospects and Research Needs. Banff, Alberta, Canada. | DEM | Automated landform classification, ecological modeling, multi-level, hierarchical ecological classification, integrated hydrological, ecological and geomorphological spatial entities; DEM | URL |
| Abstract: Resource inventory systems are at the heart of virtually all efforts to manage natural resources data. They provide the foundation for responsible management and planning and the basis for applying management knowledge and experience over space and time. In many jurisdictions, resource inventories are undergoing change in response to improvements in technology and concerns about costs and effectiveness of current methods. A new generation of classification and mapping systems is emerging that makes use of improved mapping and modeling technologies, while continuing to draw upon the existing foundation of classification and mapping protocols. A critical feature of most resource inventory systems is the definition of fundamental classes of spatial entities that can be recognized both conceptually and physically as discrete spatial entities. Most mapping systems rely on recognition of landform or landscape based spatial entities to define this basic structural framework. Landforms provide a physical framework for describing the environment and the ecological processes and interactions that occur within the environment (Rowe, 1979). Numerous investigators have examined ways in which digital elevation data can help define landform-based units to act as basic spatial and structural entities for soil, terrain or ecological maps. These investigations have demonstrated many useful concepts. To the best of our knowledge no proposed system of automated terrain or ecological mapping has advanced beyond research investigation to achieve routine, operational use. This paper describes a conceptual design for creating landform-based spatial entities from digital elevation data to support multi-level, hierarchical integrated natural resource inventory. The geomorphic/hydrologic spatial entities defined by our procedures are intended to provide a framework for mapping more specific ecological entities of interest. | ||||||
BibTeX:
@inproceedings{macmillan2000gisem4,
author = {MacMillan, Robert A. and McNabb, David H. and Jones, R. Keith},
title = {Automated landform classification using DEMs: a conceptual framework for a multi-level, hierarchy of hydrologically and geomorphologicaly oriented physiographic mapping units},
booktitle = {4th International Conference on GIS and Environmental Modeling (GIS/EM4). Problems, Prospects and Research Needs. Banff, Alberta, Canada.},
year = {2000},
url = {http://www.colorado.edu/research/cires/banff/pubpapers/198/}
}
|
||||||
| Malanson, G. P. | 1999 | Considering Complexity. [BibTeX] |
Annals of the Association of American Geographers 89 (4) , 746-753 | URL |
||
BibTeX:
@article{Malanson1999AAAG,
author = {Malanson, George P.},
title = {Considering Complexity.},
journal = {Annals of the Association of American Geographers},
year = {1999},
volume = {89},
number = {4},
pages = {746-753},
url = {http://links.jstor.org/sici?sici=0004-5608%28199912%2989%3A4%3C746%3ACC%3E2.0.CO%3B2-T}
}
|
||||||
| Marcotte, D. | 1996 | Fast variogram computation with FFT. | Computers & Geoscience 22 (10) , 1175-1186 | uncertainty | Variogram; Cross-variogram; Covariogram; Fast Fourier Transform | DOI |
| Abstract: Two programs are presented to compute direct- and cross-variograms, direct and cross-covariograms, and pseudo-cross-variograms. The programs are written in MATLAB and are based on the Fast Fourier Transform algorithm (FFT). The programs accept complete, or incomplete, regular grid data. The FFT appoach is shown to be faster than the spatial approach for this type of data. It gives exactly the same numerical variogram values as programs operating in the spatial domain. These programs could be most useful in image analysis, where images are usually 256 � 256 pixels, 512 � 512 pixels, or larger. For such large images, FFT is many orders of magnitude faster than the spatial approach. | ||||||
BibTeX:
@article{Marcotte1996CG,
author = {Marcotte, Denis},
title = {Fast variogram computation with FFT.},
journal = {Computers \& Geoscience},
year = {1996},
volume = {22},
number = {10},
pages = {1175-1186},
doi = {10.1016/S0098-3004(96)00026-X}
}
|
||||||
| Marshall, S. J. | 2002 | Modelled nucleation centres of the Pleistocene ice sheets from an ice sheet model with subgrid topographic and glaciologic parameterizations. | Quaternary International 95-96 , 125-137 | ISM | subgrids; parameterization; hypsometry; | URL |
| Abstract: Ice sheet inception at the onset of the last glacial epoch, ca. 115 kyr BP, is not well understood. To cause the Northern Hemisphere to descend into Ice Age conditions, internal climate system feedbacks must have acted to amplify relatively low-amplitude orbital cooling trends. While a number of plausible internal mechanisms have been proposed for this internal amplification, the dramatic continental ice sheet expansion that is recorded in the marine sediment record is an enduring mystery. Global sea level lowering of at least 20m and as much as 75m over 10 kyr appears typical of the early stages of glacial inception. This rate of ice sheet growth has not been freely captured in either glaciologic or climatic models. Is it because we do not adequately understand the relevant internal feedbacks, or fail to capture them in models? Is it simply related to technical model limitations, e.g. topographic resolution? This paper explores the premise that model resolution poses a critical limitation on simulations of ice sheet nucleation. I present a series of ice sheet nucleation simulations in North America and Eurasia based on an ice sheet model that includes parameterizations of km-scale topographic detail, snow/ice accumulation and melt, and glacier dynamics. Model climate is based on perturbations to modern observational climatology. Even with this topographic detail and with simulations long enough to allow ice to advect downslope and spread over the terrain, it remains difficult to induce a large-scale glacierization in both North America and Eurasia; severe climate perturbations are required. Cold temperatures need to be accompanied by substantial increases in precipitation in the North Atlantic and polar regions in order to accrue continental ice at the rate demanded by sea level reconstructions. The simulations presented here are too simple to separate climate perturbations from internal system feedbacks, but with modern precipitation rates, a combined climate cooling/net positive feedback of more than 8deg C is required to establish large-scale ice sheets in <10 kyr. With significant regional increases in moisture (50-100% more precipitation), a net mid-latitude cooling of 5-6deg C is required to achieve a sea level lowering of more than 20m in 10 kyr. I suggest that some reorganization in North Atlantic and Arctic climate in the late Eemian may be necessary to facilitate these substantial climate shifts. | ||||||
BibTeX:
@article{marshall2002qi,
author = {Marshall, Shawn J.},
title = {Modelled nucleation centres of the {Pleistocene} ice sheets from an ice sheet model with subgrid topographic and glaciologic parameterizations.},
journal = {Quaternary International},
year = {2002},
volume = {95-96},
pages = {125-137},
url = {http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6VGS-45H93Y0-R-36&_cdi=6046&_orig=browse&_coverDate=09%2F30%2F2002&_sk=999039999&view=c&wchp=dGLbVtb-zSkWz&_acct=C000049009&_version=1&_userid=946230&md5=24bd9007a2ba1752bff7ea6bb0bdec63&ie=f.pdf}
}
|
||||||
| Marshall, S. J. & Clarke, G. | 1999 | Ice sheet inception: subgrid hypsometric parameterization of mass balance in an ice sheet model. | Climate Dynamics 15 , 533-560 | ISM | ice sheet model; parameterisation | URL |
| Abstract: Abstract Studies of ice sheet inception and mountain glaciation are limited by model resolution in both atmospheric and glaciologic models. The accumulation and ablation of snow and ice are controlled by local climate, which is sensitive to topographic features that are subgrid in continent-scale investigations. Climate patterns are complex in areas of high relief, but the first-order influence of elevation on temperature and atmospheric humidity is quantifiable and is central to glacier mass balance. We make substantial improvements to the descriptions of accumulation and ablation in a large-scale ice sheet model by incorporating subgrid topographic information. The distribution of relief in the large-scale model is estimated through a hypsometric parameterization based on the minimum, maximum, and median topographic elevation. This permits accounting of high-elevation accumulation and melting in deep valleys. We combine this with a parameterization of downslope subgrid ice flux, simulating but not explicitly describing the role of alpine glaciers. The detailed budgeting of mass balance greatly improves our skill in modelling present-day ice distribution in North America. We anticipate similar improvements in our ability to model nucleation centres of the Quaternary ice sheets. This approach may also prove useful in projections of glacier and ice field response to climate change. | ||||||
BibTeX:
@article{marshall1999cd,
author = {Marshall, Shawn J. and Clarke, G.K.C.},
title = {Ice sheet inception: subgrid hypsometric parameterization of mass balance in an ice sheet model.},
journal = {Climate Dynamics},
year = {1999},
volume = {15},
pages = {533-560},
url = {http://www.springerlink.com/app/home/content.asp?wasp=6ea5d385ykcrxw4d9h2m&referrer=contribution&format=2&page=1&pagecount=18}
}
|
||||||
| Marshall, S. J., James, T. S. & Clarke, G. K. | 2002 | North American Ice Sheet reconstructions at the Last Glacial Maximum | Elsevier Quaternary Science Reviews 21 (1-3) , 175-192 | ISM | DOI |
|
| Abstract: The areal extent of the last glacial maximum (LGM) ice sheets is well known in North America, but there is no direct geological proxy for ice sheet thickness or volume. Uncertainties associated with glaciological and geophysical reconstructions give widely varying estimates of North American Ice Sheet (NAIS) volume at LGM. In an effort to quantify the uncertainty associated with glaciological reconstructions, we conducted a suite of 190 numerical simulations of the last glacial cycle in North America, prescribing different climatic, mass balance, glaciologic, and isostatic treatments for the least constrained model variables. LGM ice sheet reconstructions were evaluated using the well-established geologic record of ice sheet area and southern extent at LGM (Dyke and Prest (1987)). These constraints give a subset of 33 simulations that produce reasonable LGM ice cover in North America. Ice sheet dispositions and the associated parameter settings in this subset of tests provide insight into the plausible range of NAIS thickness, form, and mass balance regime at LGM. Ice volume in this subset of tests spans a range of 28.5–38.9×1015 m3 at LGM, with a predominant cluster at 32–36×1015 m3. Taking floating ice and displaced continental water into account, this corresponds to 69–94 m eustatic sea level (msl). More than 75% of the accepted tests fall in the range 78–88 msl. We argue that this is a plausible estimate of the volume of water locked up in the NAIS at LGM. | ||||||
BibTeX:
@article{Marshall2002QSR,
author = {Marshall, Shawn J. and James, Thomas S. and Clarke, Garry K.C.},
title = {{North American Ice Sheet reconstructions at the Last Glacial Maximum}},
journal = {Quaternary Science Reviews},
publisher = {Elsevier},
year = {2002},
volume = {21},
number = {1-3},
pages = {175-192},
doi = {10.1016/S0277-3791(01)00089-0}
}
|
||||||
| Martin, Y. & Church, M. | 2004 | Numerical modelling of landscape evolution: geomorphological perspectives. | Progress in Physical Geography 28 (3) , 317-339 | geomorphology • landscape evolution • model implementation • numerical modelling • process specification • scale | DOI URL |
|
| Abstract: A resurgence of interest in landscape evolution has occurred as computational technology has made possible spatially and temporally extended numerical modelling. We review elements of a structured approach to model development and testing. It is argued that natural breaks in landscape process and morphology define appropriate spatial domains for the study of landscape evolution. The concept of virtual velocity is used to define appropriate timescales for the study of landscape change. Process specification in numerical modelling requires that the detail incorporated into equations be commensurable with the particular scale being considered. This may entail a mechanistic approach at small (spatial) scales, whereas a generalized approach to process definition may be preferred in large-scale studies. The distinction is illustrated by parameterizations for hillslope and fluvial transport processes based on scale considerations. Issues relevant to model implementation, including validation, verification, calibration and confirmation, are discussed. Finally, key developments and characteristics associated with three approaches to the study of landscape modelling:(i) conceptual; (ii) quasi-mechanistic; and (iii) generalized physics, are reviewed. | ||||||
BibTeX:
@article{Martin2004PPG,
author = {Martin, Yvonne and Church, Michael},
title = {Numerical modelling of landscape evolution: geomorphological perspectives.},
journal = {Progress in Physical Geography},
year = {2004},
volume = {28},
number = {3},
pages = {317-339},
url = {http://ppg.sagepub.com/cgi/content/abstract/28/3/317},
doi = {10.1191/0309133304pp412ra}
}
|
||||||
| Martinoni, D. | 2002 | Models and Experiments for Quality Handling in Digital Terrain Modelling. [BibTeX] |
University of Zurich, Dept.~of Geography | DEM | ||
BibTeX:
@phdthesis{Martinoni2002phd,
author = {Daria Martinoni},
title = {Models and Experiments for Quality Handling in Digital Terrain Modelling.},
school = {University of Zurich, Dept.~of Geography},
year = {2002}
}
|
||||||
| Matheron, G. | 1969 | Principles of Geostatistics. | Economical Geology 58 , 1246-1266 | URL |
||
| Abstract: Whereas classical statistical methods treat the value of individual samples as though they were governed by chance, geostatistics takes into account the effect of sample location, e.g., that samples close to one another are more likely to have similar grades than samples far apart. Geostatistics is therefore particularly useful in geologic applications, such as evaluation of mineral deposits. General principles are outlined, with examples. | ||||||
BibTeX:
@article{Matheron1969EcoGeol,
author = {Matheron, G.},
title = {Principles of Geostatistics.},
journal = {Economical Geology},
year = {1969},
volume = {58},
pages = {1246-1266},
url = {http://econgeol.geoscienceworld.org/cgi/content/abstract/58/8/1246}
}
|
||||||
| MATLAB | 2006 | R2006b Documentation. [BibTeX] |
The Mathworks Inc. | |||
BibTeX:
@manual{matlab,
author = {MATLAB},
title = {R2006b Documentation.},
year = {2006}
}
|
||||||
| McCulloch, R., Bentley, M., Purves, R., Hulton, N. R., Sugden, D. E. & Clapperton, C. | 2000 | Climatic inferences from glacial and palaeoecological evidence at the last glacial termination, southern South America. | Journal of Quaternary Science 15 (4) , 409-417 | ISM | South America; Patagonia; last glacial termination; palaeoecology; ice sheets. | URL |
| Abstract: There is uncertainty about the interhemispheric timing of climatic changes during the last glacial interglacial transition. Different hypotheses, relying on different lines of evidence, point variously to the Northern Hemisphere leading the Southern Hemisphere and vice versa, or to synchrony between the hemispheres. Southern South America is well placed to test the various alternatives using both glacial and palaeoecological evidence. We argue here from a synthesis of key proxy records that there was a sudden rise in temperature that initiated deglaciation sychronously over 16? of latitude at 14 600 14 300 14C yr BP (17 500 17 150 cal. yr). There was a second step of warming in the Chilean Lake District at 13 000 12 700 14C yr BP (15 650 15 350 cal. yr), which saw temperatures rise to close to modern values. A third warming step, particularly clear in the south, occurred at ca. 10 000 14C yr BP (11 400 cal. yr), the latter achieving Holocene levels of warmth. Following the initial warming, there was a lagged response in precipitation as the westerlies, after a delay of ca. 1600 yr, migrated from their northern glacial location to their present latitude, which was attained by 12 300 14C yr BP (14 300 cal. yr). The latitudinal contrasts in the timing of maximum precipitation are reflected in regional contrasts in vegetation change and in glacier behaviour. The large scale of a 80-km glacier advance in the Strait of Magellan at 12 700 10 300 14C yr BP (15 350 12 250 cal. yr), which spans the Antarctic Cold Reversal and the Younger Dryas, was influenced by the return of the westerlies to southern latitudes. The delay in the migration of the westerlies coincides with the Heinrich 1 iceberg event in the North Atlantic. The suppressed global thermohaline circulation at the time may have affected sea-surface temperatures in the South Pacific, and the return of the westerlies to their present southerly latitude only followed ocean reorganisation to its present interglacial mode. | ||||||
BibTeX:
@article{mcculloch2000jqs,
author = {McCulloch, R.D. and Bentley, M.J. and Purves, R.S. and Hulton, Nicholas R.J. and Sugden, David E. and Clapperton, C.M.},
title = {Climatic inferences from glacial and palaeoecological evidence at the last glacial termination, southern South America.},
journal = {Journal of Quaternary Science},
year = {2000},
volume = {15},
number = {4},
pages = {409-417},
url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/72508322/PDFSTART}
}
|
||||||
| Miller, H. J. & Wentz, E. A. | 2003 | Representation and Spatial Analysis in Geographic Information Systems. [BibTeX] |
Annals of the Association of American Geographers 93 (3) , 574-594 | uncertainty | geographic information system; geographic representation; spatial analysis | |
BibTeX:
@article{miller2003aaag,
author = {Miller, Harvey J. and Wentz, Elisabeth A.},
title = {Representation and Spatial Analysis in Geographic Information Systems.},
journal = {Annals of the Association of American Geographers},
year = {2003},
volume = {93},
number = {3},
pages = {574-594}
}
|
||||||
| Mineter, M. & Hulton, N. R. | 2001 | Parallel processing for finite-difference modelling of ice sheets. | Computers & Geoscience 27 , 829-838 | ISM | Environmental modelling; High-performance computing; Parallel algorithms; Glaciology; ice sheet model | |
| Abstract: Improved modelling of ice sheets, by use of high resolution and with representation of more physical processes, is constrained by long run-times even on the latest single-processor workstation. Parallel processing therefore has a role to play. This paper describes techniques for the parallel processing of ice sheet models and presents design approaches for both the Cray T3 series and other parallel architectures. An implementation of a fully coupled, thermodynamic, 3D ice sheet model is described for the Cray T3D and is shown to be scaleable and efficient. | ||||||
BibTeX:
@article{mineter2001cg,
author = {Mineter, Michael and Hulton, Nicholas R.J.},
title = {Parallel processing for finite-difference modelling of ice sheets.},
journal = {Computers \& Geoscience},
year = {2001},
volume = {27},
pages = {829-838}
}
|
||||||
| Monmonier, M. | 2006 | Cartography: uncertainty, interventions, and dynamic display. [BibTeX] |
Progress in Human Geography 30 (3) , 373-381 | DOI |
||
BibTeX:
@article{Monmonier2006PHG,
author = {Monmonier, Mark},
title = {Cartography: uncertainty, interventions, and dynamic display.},
journal = {Progress in Human Geography},
year = {2006},
volume = {30},
number = {3},
pages = {373-381},
doi = {10.1191/0309132506ph612pr}
}
|
||||||
| Montgomery, D. R. | 2001 | Slope distributions, threshold hillslopes, and steady-state topography. | American Journal of Science 301 (4-5) , 432-454 | URL |
||
| Abstract: Digital elevation models of two "steady-state" mountain ranges, the Olympic Mountains (OM) and Oregon Coast Range (OCR), are used to examine relationships between slope distributions, the development of threshold hillslopes, and steady-state topography. Plots of drainage area versus slope for these mountain ranges exhibit substantial scatter that complicates comparison of range form to analytical theories and landscape evolution models. Contour plots of the density of such data reveal an attractor at the scale of the transition from hillslope processes to channel processes, and log-bin averaging reveals trends that parallel predictions of steady-state erosion laws but with different rate laws for five distinct process domains: hillslopes, valley heads, and colluvial, bedrock, and alluvial valley segments. Slope histograms computed for 100 km2 areas (defined by a 10 x 10 km grid) throughout the OM exhibit approximately normal or exponential distributions in areas of active rock uplift and depositional topography, respectively. Local slope distributions in the OCR also tend to be normally distributed, but some are left-skewed in areas with gentler slopes. Mean slopes determined both over the above referenced grid and a 10-km diam moving window are relatively invariant in the core of the OM in spite of strong contrasts in bedrock erodibility and gradients in long-term rock uplift rates. In contrast, the mean slopes in the OCR parallel latitudinal gradients in rock uplift rates and bedrock erodibility. Hence, the slope distributions in the OM and OCR reflect distinct relationships between development of threshold bedrock and soil-mantled hillslopes and steady-state topography. | ||||||
BibTeX:
@article{montgomery2001sdt,
author = {Montgomery, David R.},
title = {Slope distributions, threshold hillslopes, and steady-state topography.},
journal = {American Journal of Science},
year = {2001},
volume = {301},
number = {4-5},
pages = {432-454},
url = {http://www.ajsonline.org/cgi/content/abstract/301/4-5/432}
}
|
||||||
| Moore, I., Grayson, R. & Ladson, A. | 1991 | Digital terrain modelling: A review of hydrological, geomorphological, and biological applications. | Hydrological Processes 5 (1) , 3-30 | Basin topography • Digital elevation models • Terrain analysis • Hydrologic models | DOI |
|
| Abstract: The topography of a catchment has a major impact on the hydrological, geomorphological, and biological processes active in the landscape. The spatial distribution of topographic attributes can often be used as an indirect measure of the spatial variability of these processes and allows them to be mapped using relatively simple techniques. Many geographic information systems are being developed that store topographic information as the primary data for analysing water resource and biological problems. Furthermore, topography can be used to develop more physically realistic structures for hydrologic and water quality models that directly account for the impact of topography on the hydrology. Digital elevation models are the primary data used in the analysis of catchment topography. We describe elevation data sources, digital elevation model structures, and the analysis of digital elevation data for hydrological, geomorphological, and biological applications. Some hydrologic models that make use of digital representations of topography are also considered. | ||||||
BibTeX:
@article{Moore1991HP,
author = {Moore, I.D. and Grayson, R.B. and Ladson, A.R.},
title = {Digital terrain modelling: A review of hydrological, geomorphological, and biological applications.},
journal = {Hydrological Processes},
year = {1991},
volume = {5},
number = {1},
pages = {3-30},
doi = {10.1002/hyp.3360050103}
}
|
||||||
| Moran, P. | 1950 | Notes on continuous stochastic phenomena. [BibTeX] |
Biometrika 37 , 17-23 | uncertainty | ||
BibTeX:
@article{Moran1950Biometrika,
author = {Moran, P.A.P.},
title = {Notes on continuous stochastic phenomena.},
journal = {Biometrika},
year = {1950},
volume = {37},
pages = {17-23}
}
|
||||||
| Murray, A. B. | 2007 | Reducing model complexity for explanation and prediction. | Geomorpholgy 90 (3-4) , 178-191 | DEM, subgrids | Modeling; Numerical model; Complexity; Complex systems; Emergence; Reductionism; Cellular models | DOI |
| Abstract: Numerical models can be useful for explaining poorly understood phenomena or for reliable quantitative predictions. When modeling a multi-scale system, a ‘top-down’ approach�basing models on emergent variables and interactions, rather than explicitly on the much faster and smaller scale processes that give rise to them�facilitates both goals. Parameterizations representing emergent interactions range from highly simplified and abstracted to more quantitatively accurate. Empirically based large-scale parameterizations lead more reliably to accurate large-scale behavior than do parameterizations of much smaller scale processes. Conversely, purposefully simplified representations of model interactions can enhance a model's utility for explanation, clarifying the key feedbacks leading to an enigmatic behavior. For such potential insights to be relevant, the interactions in the model need to correspond to those in the ‘real’ system in some straightforward way. Such a correspondence usually holds for models constructed for predictive purposes, although this is not a requirement. The goals motivating a modeling endeavor help determine the most appropriate modeling strategies, as well as the most appropriate criteria for judging model usefulness. | ||||||
BibTeX:
@article{Murray2007Geomorpholgy,
author = {Murray, A. Brad},
title = {Reducing model complexity for explanation and prediction.},
journal = {Geomorpholgy},
year = {2007},
volume = {90},
number = {3-4},
pages = {178-191},
doi = {10.1016/j.geomorph.2006.10.020}
}
|
||||||
| Murray, T. | 1997 | Assessing the paradigm shift: deformable glacier beds. | Quaternary Science Reviews 16 (9) , 995-1016 | ISM | review; glacier beds; sediment; deformation | DOI |
| Abstract: During the mid-1980s, glaciologists recognised that many glaciers and ice masses overlie soft sediments rather than hard bedrock. These sediments are typically weaker than glacier ice and may, therefore, deform. This realisation was heralded as a 'paradigm shift in glaciology'. Since this realisation, a wide body of theoretical and field based research has been undertaken to assess the mechanical and hydrological significance of such substrates. We review the techniques and results of this work and attempt to assess this 'paradigm shift in glaciology' and in particular its importance for Quaternary scientists. We suggest areas of research that remain unanswered, and identify those in which glacial geology, in particular, may be able to inform glaciologists. QSR | ||||||
BibTeX:
@article{murray1997qsr,
author = {Murray, Tavi},
title = {Assessing the paradigm shift: deformable glacier beds.},
journal = {Quaternary Science Reviews},
year = {1997},
volume = {16},
number = {9},
pages = {995-1016},
doi = {10.1016/S0277-3791(97)00030-9}
}
|
||||||
| Näslund, J., Fastook, J. L. & Holmlund, P. | 2000 | Numerical modelling of the ice sheet in western Dronning Maud Land, East Antarctica: impacts of present, past and future climates. | Journal of Glaciology 46 (152) , 54-66 | ISM | ice sheet model; mass balance parameterization | URL |
| Abstract: Time-dependent ice-sheet modelling of a 176 000 km2 area in western Dronning Maud Land, East Antarctica, provided information on the ice sheet's response to six climate-change scenarios. Another experiment was done to study changes in ice thickness, flow and basal temperature conditions between the present ice configuration and a simulated maximum palaeo-ice sheet. The input to the model included new datasets of bed and surface topography compiled for this study. The results of the six climate-change experiments, including a 0.5°C per century global-warming scenario, show that the ice sheet has a robust behaviour with respect to the different climate changes. The maximum change in ice volume was <5% of the initial volume in all climate runs. This is for only relatively short-term climate changes without major changes in global sea level, and also a simulated ice sheet without an ice shelf. The modelled long-term response time of the ice sheet, 20 kyr or more, indicates that the ice sheet may still be adjusting to the climate change that ended the Last Glacial Maximum. In the maximum palaeo-ice-sheet simulation, with a 5°C climate cooling and the grounding line located at the continental-shelf margin, ice thickness increased drastically downstream from the Heimefrontfjella mountain range but remained basically unaffected on the upstream polar plateau. Com- pared to present conditions, complex changes in basal temperatures were observed. The extent of areas with basal melting increased, for example in the deep trough of the Vest- straumen ice stream. Areas at intermediate elevations in the landscape also experienced increased basal temperatures, with significant areas reaching the melting point. In contrast, high-altitude areas that today are clearly cold-based, such as around Heimefrontfjella and Vestfjella and the Högisen dome, experienced a 5–10°C decrease in basal temperatures in the palaeo-ice-sheet reconstruction. The results suggest that the alpine landscape within these mountain regions was formed by wet-based local glaciers and ice sheets prior to the late Cenozoic. | ||||||
BibTeX:
@article{naeslund2000jgla,
author = {N\"aslund, Jens-Ove and Fastook, James L. and Holmlund, P.},
title = {Numerical modelling of the ice sheet in western Dronning Maud Land, East Antarctica: impacts of present, past and future climates.},
journal = {Journal of Glaciology},
year = {2000},
volume = {46},
number = {152},
pages = {54-66},
url = {http://www.ingentaconnect.com/content/igsoc/jog/2000/00000046/00000152/art00009}
}
|
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| Näslund, J., Jansson, P., Fastook, J. L., Johnson, J. & Andersson, L. | 2005 | Detailed spatially distributed geothermal heat-flow data for modeling of basal temperatures and meltwater production beneath the Fennoscandian ice sheet. | Annals of Glaciology 40 (1) , 95-101 | URL |
||
| Abstract: Accurate modeling of ice sheets requires proper information on boundary conditions, including the geothermal heat flow (or heat-flow density (HFD)). Traditionally, one uniform HFD value is adopted for the entire modeled domain. We have calculated a distributed, high-resolution HFD dataset for an approximate core area (Sweden and Finland) of the Scandinavian ice sheet, and imbedded this within lower-resolution data published for surrounding regions. Within the Last Glacial Maximum ice margin, HFD varies with a factor of as much as 2.8 (HFD values ranging between 30 and 83 mW m−2), with an average of 49 mW m−2. This average value is 17% higher than 42 mW m−2, a common uniform value used in ice-sheet modeling studies of Fennoscandia. Using this new distributed dataset on HFD, instead of a traditional uniform value of 42 mW m−2, yields a 1.4 times larger total basal meltwater production for the last glacial cycle. Furthermore, using the new dataset in high-resolution modeling results in increased spatial thermal gradients at the bed. This enhances and introduces new local and regional effects on basal ice temperatures and melt rates. We observed significant strengthening of local 'ice streaming', which in one case correlates to an ice-flow event previously interpreted from geomorphology. Regional to local variations in geothermal heat flow need to be considered for proper identification and treatment of thermal and hydraulic bed conditions, most likely also when studying Laurentide, Greenland and Antarctic ice sheets. | ||||||
BibTeX:
@article{Naslund2005AGla,
author = {N\"aslund, Jens-Ove and Jansson, Peter and Fastook, James L. and Johnson, Jesse and Andersson, Leif},
title = {Detailed spatially distributed geothermal heat-flow data for modeling of basal temperatures and meltwater production beneath the Fennoscandian ice sheet.},
journal = {Annals of Glaciology},
year = {2005},
volume = {40},
number = {1},
pages = {95-101},
url = {http://www.ingentaconnect.com/content/igsoc/agl/2005/00000040/00000001/art00017}
}
|
||||||
| Namikawa, L. M. & Renschler, C. S. | 2004 | Uncertainty in digital elevation data used for geophysical flow simulation. [BibTeX] |
Geoinfo 2004, Proceedings of the VI. Brazilian Symposium on GeoInformatics. | DEM | ||
BibTeX:
@inproceedings{namikawa2004proc,
author = {Namikawa,Laércio M. and Renschler, Chris S.},
title = {Uncertainty in digital elevation data used for geophysical flow simulation.},
booktitle = {Geoinfo 2004, Proceedings of the VI. Brazilian Symposium on GeoInformatics.},
year = {2004}
}
|
||||||
| Napieralski, J. | 2007 | GIS and Field-Based Spatiotemporal Analysis for Evaluation of Paleo–Ice Sheet Simulations. | The Professional Geographer 59 (2) , 173-183 | GIS, ISM | DOI |
|
| Abstract: Reconstructing paleo-ice sheets is significant for paleoclimate reconstructions and evaluations of sea level low stands. Accurate reconstructions of paleo-ice sheet dimensions and dynamics necessitate the combination of field evidence and process modeling. In this study, a GIS-based technique was developed to quantitatively assess model output against geomorphic data. However, implementation of this technique is not straightforward and requires consideration of time-space relationships, data representation, resolution, and analytical design. Combined use of two software tools holds considerable promise for the use, application, and interpretation of refined ice sheet models. | ||||||
BibTeX:
@article{Napieralski2007TPG,
author = {Napieralski, Jacob},
title = {{GIS} and Field-Based Spatiotemporal Analysis for Evaluation of Paleo–Ice Sheet Simulations.},
journal = {The Professional Geographer},
year = {2007},
volume = {59},
number = {2},
pages = {173-183},
doi = {10.1111/j.1467-9272.2007.00605.x}
}
|
||||||
| NGDC | 2006 | National Geophysical Data Center, 2-Minute Gridded Global Relief Data (ETOPO2v2) [BibTeX] |
||||
BibTeX:
@misc{ETOPO2006,
author = {{NGDC}},
title = {{National Geophysical Data Center, 2-Minute Gridded Global Relief Data (ETOPO2v2)}},
year = {2006}
}
|
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| Nye, J. | 1957 | The distribution of stress and velocity in glaciers and ice sheets. [BibTeX] |
Proceedings of the Royal Society of London Sr A 239 , 113-133 | |||
BibTeX:
@article{nye1957prslsa,
author = {Nye, J.F.},
title = {The distribution of stress and velocity in glaciers and ice sheets.},
journal = {Proceedings of the Royal Society of London Sr A},
year = {1957},
volume = {239},
pages = {113-133}
}
|
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| Oehler, S. | 2005 | Visualisierung von Unsicherheiten unter Einbezug grossraeumiger Modellierungsdaten. | Diplomarbeit Geographisches Institut der Universitaet Zuerich | uncertainty visualisation | uncertainty; visualisation; bernin; java | URL |
| Abstract: Error free models do not exist. There are always limitations in either mesuring the input parameters or by not knowing all parameters influencing the model. Since the result output of the models is used in decision making, it is very important to provide the decision makers with all known uncertainties concerning the specific model. This diploma thesis examines different visualisation possibilities of data uncertainties. The term data uncertainties describes differences or value fluctuations in various output data sets. These differences originate, for example, from models which supply differing result sets from different input parameters, as it is usual with the employment of Monte Carlo Simulation. Data uncertainties or data inaccuracies arise throughout the entire sequence of data processing. They are unavoidably linked to any kind of data. A selection of several sources of data uncertainty are presented in the chapter ‚Grundlagen’ (fundamentals). The theoretical framework applied for the visualization of uncertainties is based on the famous graphic variables described by Jaques Bertin in 1967. Newer graphical variables and more complex visualization techniques are also analyzed. A large amount of visualization options are conceivable, some of which are tackled in the chapter ‚Implementierung’ (implementation). The central aim of this diploma thesis is to provide a concrete solution to the problem by implementing a bespoke application. This application is described in detail in the regarding chapter. In its actual version the application is able to produce representations of original data records and differences between two of such original data records. Data sets of ice sheet models of the fennoscandian ice body are used as sample data. They are available in the netCDF format, to which the data interface of the application is limited. An extension of the application to other data formats should not cause large problems. For the evaluation of the implemented visualizations and the application itself, an evaluation exercise was undertaken. This was arranged in the context of an open interview, combined with a short, standardized questionnaire. For becoming acquainted with the application, the test persons received different tasks. They had to solve them with support of the test leader. The results of this evaluation can be classified as highly positive. The application, the visualizations and the visualisation concept are evaluated as interessting and useful. The highest acceptance could gain the most simple bivariate visualisation, which can give a good overview of the data and their uncertainties within a few seconds. More complex visualisations are less popular. The application itself can be improved by implementing more visualisation options and more functionality. Especially the GUI should be adjusted |
||||||
BibTeX:
@mastersthesis{Oehler2005msc,
author = {Oehler, Sascha},
title = {Visualisierung von Unsicherheiten unter Einbezug grossraeumiger Modellierungsdaten.},
school = {Geographisches Institut der Universitaet Zuerich},
year = {2005},
url = {http://www.geo.unizh.ch/~fhebeler/soehler06_unsicherheitsvisualisierung.pdf}
}
|
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| Oerlemans, J. | 2002 | On glacial inception and orography. | Quaternary International 95 96 , 5-10 | ISM | ISM; glaciology; | URL |
| Abstract: There is no doubt that orography plays a crucial role in the initiation of ice sheets. Mass balance observations on glaciers in highmountain and polar climates show that the specific balance varies first of all with altitude. The height mass balance feedback (HMB-feedback) is the most effective process to turn local ice caps into big ice sheets. Here, a study is presented on the processes that determine the strength of the HMB-feedback. This is done by carrying out a set of integrations with a numerical ice-sheet model for a bounded domain and a sinusoidally varying bed shape. Results are analysed for different wavenumbers and amplitudes. It turns out that the relative importance of the geometric effect (higher mountains allow earlier glacierisation) and the ice-mechanical effect (dependence of ice flow on the bed slope) varies significantly with wavenumber and amplitude. With regard to full glaciation of the domain, this implies that for a given wavenumber there is a preferred amplitude (that is, the drop in the equilibrium-line altitude needed to initiate full glaciation has a minimum). | ||||||
BibTeX:
@article{oerlemans2002qi,
author = {Oerlemans, J.},
title = {On glacial inception and orography.},
journal = {Quaternary International},
year = {2002},
volume = {95 96},
pages = {5-10},
url = {http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6VGS-45H93Y0-5-1P&_cdi=6046&_orig=browse&_coverDate=09%2F30%2F2002&_sk=999039999&view=c&wchp=dGLbVtb-zSkWz&_acct=C000049009&_version=1&_userid=946230&md5=85ec057c62a022e297e1518696a8a20e&ie=f.pdf}
}
|
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| Oerlemans, J. | 1988 | Simulation of historic glacier variations with a simple climate-glacier model. [BibTeX] |
Journal of Glaciology 34 (118) , 333-341 | ISM | climate glacier model | |
BibTeX:
@article{oerlemans1988jgla,
author = {Oerlemans, J.},
title = {Simulation of historic glacier variations with a simple climate-glacier model.},
journal = {Journal of Glaciology},
year = {1988},
volume = {34},
number = {118},
pages = {333-341}
}
|
||||||
| Oerlemans, J. | 1980 | Model experiments on the 100,000-yr glacial cycle. | Nature 287 , 430-432 | ISM | DOI URL |
|
| Abstract: It is believed that during the Quaternary era changes in global ice volume were mainly due to changes in the size of the ice sheets on the Eurasian and American continents. Time spectra of oxygen isotope records from deep-sea cores and of the Earth's orbital parameters are remarkably similar in the 10,000−120,000-yr range1,2, suggesting that changes in global ice volume are forced by insolation variations. Model studies by Weertman3,4 and Pollard5 have confirmed this point to some extent: the 20,000- and 40,000-yr cycles can be reproduced, but the 100,000-yr cycle does not show up. Recently, Imbrie and Imbrie6 have fitted simple nonlinear mathematical models to delta 18O curves. They found that reasonable fits are obtained if the time scale for ice-sheet growth is about 27,000 yr and for decay about 7,000 yr. The present study considers the problem of the 100,000-yr cycle in a similar way. Experiments with a Northern Hemisphere ice-sheet model show that the 100,000-yr cycle and its sawtooth shape may be explained by ice sheet/bedrock dynamics alone. This cycle seems to be an internally generated feature and is not forced by variations in the eccentricity of the Earth's orbit. | ||||||
BibTeX:
@article{Oerlemans1980Nature,
author = {Oerlemans, J.},
title = {Model experiments on the 100,000-yr glacial cycle.},
journal = {Nature},
year = {1980},
volume = {287},
pages = {430-432},
url = {http://www.nature.com/nature/journal/v287/n5781/pdf/287430a0.pdf},
doi = {10.1038/287430a0}
}
|
||||||
| Oerlemans, J., Anderson, B., Hubbard, A., Huybrechts, P., Jóhannesson, T., Knap, W., Schmeits, M., Stroeven, A., van de Wal, R., Wallinga, J. & Zuo, Z. | 1998 | Modelling the response of glaciers to climate warming. | Climate Dynamics 14 , 267-274 | ISM | DOI |
|
| Abstract: Dynamic ice-flow models for 12 glaciers and ice caps have been forced with various climate change scenarios. The volume of this sample spans three orders of magnitude. Six climate scenarios were considered: from 1990 onwards linear warming rates of 0.01, 0.02 and 0.04qK a-1, with and without concurrent changes in precipitation. The models, calibrated against the historic record of glacier length where possible, were integrated until 2100. The differences in individual glacier responses are very large. No straightforward relationship between glacier size and fractional change of ice volume emerges for any given climate scenario. The hypsometry of individual glaciers and ice caps plays an important role in their response, thus making it difficult to generalize results. For a warming rate of 0.04qK a-1, without increase in precipitation, results indicate that few glaciers would survive until 2100. On the other hand, if the warming rate were to be limited to 0.01qK a-1 with an increase in precipitation of 10% per degree warming, we predict that overall loss would be restricted to 10 to 20% of the 1990 volume. | ||||||
BibTeX:
@article{Oerlemans1998CD,
author = {Oerlemans, J. and Anderson, B. and Hubbard, A. and Huybrechts, P. and J\'{o}hannesson, T. and Knap, W.H. and Schmeits, M. and Stroeven, A.P. and van de Wal, R.S.W. and Wallinga, J. and Zuo, Z.},
title = {Modelling the response of glaciers to climate warming.},
journal = {Climate Dynamics},
year = {1998},
volume = {14},
pages = {267-274},
doi = {10.1007/s003820050222}
}
|
||||||
| Oerlemans, J. & Hoogendoorn, N. | 1989 | Mass balance gradients and climatic change. [BibTeX] |
Quaternary Science Reviews 35 (121) , 399-405 | ISM | mass balance; mass balance profile; altitude; perturbation | |
BibTeX:
@article{oerlemans1989jgla,
author = {Oerlemans, J. and Hoogendoorn, N.C.},
title = {Mass balance gradients and climatic change.},
journal = {Quaternary Science Reviews},
year = {1989},
volume = {35},
number = {121},
pages = {399-405}
}
|
||||||
| Ohmura, A., Kasser, P. & Funk, M. | 1992 | Climate at the equilibrium line of glaciers. [BibTeX] |
Journal of Glaciology 38 (130) , 397-408 | ISM | ELA, glaciers, climate, radiation, precipitation, mass balance, meteorological | |
BibTeX:
@article{ohmura1992jgla,
author = {Ohmura, Atsumu and Kasser, Peter and Funk, Martin},
title = {Climate at the equilibrium line of glaciers.},
journal = {Journal of Glaciology},
year = {1992},
volume = {38},
number = {130},
pages = {397-408}
}
|
||||||
| Oksanen, J. | 2003 | Tracing the gross errors of DEM - visualisation techniques for preliminary quality analysis. | Proceedings of the 21st International Cartographic Conference (ICC) ICA | DEM | DEM; error; visualisation; | |
| Abstract: The paper presents visualization techniques that can be used in preliminary quality analysis of Digital Elevation Models (DEM). The aim was to reveal the gross errors in DEM as they appear to be a serious limiting factor on DEM usability in terrain analysis. Here the focus is on elevation models based on contour or other topographic data, but the techniques are also applicable to DEMs generated from other data sources. Three types of errors are found in DEMs: 1) gross errors, 2) systematic errors, and 3) random errors. To be able to analyse systematic and random errors, gross errors have to be eliminated. From the statistical viewpoint this is obvious, but in DEM quality analysis the fact is annoyingly often overlooked. Examples of this can be found from many national mapping agencies, which report the root mean square error or standard deviation in vertical height error statistics of DEMs, which may still have gross errors. Gross errors in DEMs include serious topographical misinterpretations during the mapping process and the appearance of surface artefacts caused by erroneously used DEM approximation techniques. Gross errors can be perceived using independent reference data, but errors related to DEM approximation in particular are also likely to be revealed with appropriate surface visualization techniques, such as remainder image technique, relief shading and multi-band variation of it, or convolution techniques. The techniques can be used to support decisions in three different phases of DEM processing: 1) production, 2) accuracy assessment, and 3) usability analysis. From the data and the metadata producer's viewpoint, the use of visualization techniques can be helpful in the product development and documentation processes. For the individual DEM user, the techniques give valuable additional information on the usability of the DEM for specific terrain analysis purposes. | ||||||
BibTeX:
@inproceedings{Oksanen2003procicc,
author = {Oksanen, Juha},
title = {Tracing the gross errors of {DEM} - visualisation techniques for preliminary quality analysis.},
booktitle = {Proceedings of the 21st International Cartographic Conference (ICC)},
year = {2003}
}
|
||||||
| Oksanen, J. & Sarjakoski, T. | 2006 | Uncovering the statistical and spatial characteristics of fine toposcape DEM error. | International Journal of Geographical Information Science 20 (4) , 345-369 | DEM | DEM ; uncertainty; GIS; error modelling;LIDAR; Accuracy assessment; geostatistics | DOI |
| Abstract: The aim of our study was to characterize statistical and spatial details of the errors in a fine toposcale DEM derived by contour data. The fine toposcale DEMs are typically represented in a 5–50 m grid and used in the application scale 1:10 000–1:50 000. The errors were determined by using high quality reference data covering the entire study area from an airborne laser scanner. The work was motivated because of the essential role played by the correct characterization of DEM error in error propagation studies. The results showed that the spatial autocorrelation of the fine toposcale DEM error was the result of a complex combination of random and systematic-like components, and its appropriate modelling by geostatistical methods is problematic because of the small extent of the areas in which the assumption of stationarity is valid. In addition, describing the shape of the DEM error distribution was impossible with a single parameter of dispersion. This was due to a large number of outliers, which suggests that more robust descriptors of the error should be used in addition to conventional error statistics. | ||||||
BibTeX:
@article{Oksanen2006IJGIS,
author = {Oksanen, Juha and Sarjakoski, Tapani},
title = {Uncovering the statistical and spatial characteristics of fine toposcape {DEM} error.},
journal = {International Journal of Geographical Information Science},
year = {2006},
volume = {20},
number = {4},
pages = {345-369},
doi = {10.1080/13658810500433891}
}
|
||||||
| Oksanen, J. & Sarjakoski, T. | 2005 | Error propagation of DEM-based surface derivatives. | Computers & Geoscience 31 (8) , 1015-1027 | DEM | Error modelling; Geostatistics; Simulation; Digital elevation models; Spatial analysis; DEM; uncertainty; DEM error surface; | DOI |
| Abstract: This paper presents research showing how random errors in a fine toposcale digital elevation model (DEM) are propagated to DEM-based surface derivatives. The focus was on two constrained derivatives, slope and aspect, and one unconstrained derivative, drainage basin delineation. The error propagation was explored by using numerical and analytical methods, and in both approaches the DEM error was modelled as a second-order stationary Gaussian random process. The results were summarised in the case study, in which 32 realistic scenarios of DEM error models were used. The scenarios were based on exponential and Gaussian spatial autocorrelation models with four sills (0.0625, 0.25, 1.00, and 4.00 m2) and practical ranges (0, 30, 60, and 120 m). We found that, as expected, increase in DEM error increased the error in surface derivatives. However, contrary to expectations, the spatial autocorrelation model appears to have varying effects on the error propagation analysis depending on the application. In constrained surface derivatives, such as slope and aspect, the maximum error in results appeared to exist when the practical range of the error's spatial autocorrelation was roughly equal to the size of the surface derivative's calculation window. In unconstrained terrain analysis, such as drainage basin delineation, the variance of the results appeared to increase while the spatial autocorrelation range increases. Until now, the use of spatially uncorrelated DEM error models have been considered as a ‘worst-case scenario’, but this opinion may now be challenged because none of the DEM derivatives investigated in the study had maximum variation with spatially uncorrelated random error. In addition, the study revealed that the role of the appropriate shape of the spatial autocorrelation model, either exponential or Gaussian, was not as important as the choice of appropriate autocorrelation parameters: practical range and sill. However, the shape of the spatial autocorrelation model appeared to have more influence on the calculation of slope and aspect than on the drainage basin delineation. For error propagation analysis purposes an analytical approach appears to be more useful for constrained derivatives, while the Monte Carlo method is appropriate for analysing both constrained and unconstrained derivatives. |
||||||
BibTeX:
@article{Oksanen2005CG,
author = {Oksanen, Juha and Sarjakoski, Tapani},
title = {Error propagation of {DEM}-based surface derivatives.},
journal = {Computers \& Geoscience},
year = {2005},
volume = {31},
number = {8},
pages = {1015-1027},
doi = {doi:10.1016/j.cageo.2005.02.014}
}
|
||||||
| Oksanen, J. & Sarjakoski, T. | 2005 | Error propagation analysis of DEM-based drainage basin delineation. | International Journal of Remote Sensing 26 (14) , 3085-3102 | DEM | DOI |
|
| Abstract: GIS analysis-based drainage basin delineation has become an attractive alternative to traditional manual delineation methods since the availability and accuracy of Digital Elevation Models (DEMs) and topographic databases has been improved. To investigate the uncertainty in the automatic delineation process, the present study represents a process-convolution-based Monte Carlo simulation tool that offers a powerful framework for investigating DEM error propagation with thousands of GIS-analysis repetitions. Monte Carlo-based probable drainage basin delineations and manual delineations performed by five experts in hydrology or physical geography were also compared. The results showed that automatic drainage basin delineation is very sensitive to DEM uncertainty. The model of this uncertainty can be used to find out the lower bound for the size of drainage basins that can be delineated with sufficient accuracy. |
||||||
BibTeX:
@article{Oksanen2005IJRS,
author = {Oksanen, Juha and Sarjakoski, Tapani},
title = {Error propagation analysis of {DEM}-based drainage basin delineation.},
journal = {International Journal of Remote Sensing},
year = {2005},
volume = {26},
number = {14},
pages = {3085-3102},
doi = {10.1080/01431160500057947}
}
|
||||||
| Oliver, M. & Webster, R. | 1990 | Kriging: a method of interpolation for geographical information systems. | International Journal of Geographical Information Science 4 (3) , 313-332 | GIS | DOI |
|
| Abstract: Geographical information systems could be improved by adding procedures for geostatistical spatial analysis to existing facilities. Most traditional methods of interpolation are based on mathematical as distinct from stochastic models of spatial variation. Spatially distributed data behave more like random variables, however, and regionalized variable theory provides a set of stochastic methods for analysing them. Kriging is the method of interpolation deriving from regionalized variable theory. It depends on expressing spatial variation of the property in terms of the variogram, and it minimizes the prediction errors which are themselves estimated. We describe the procedures and the way we link them using standard operating systems. We illustrate them using examples from case studies, one involving the mapping and control of soil salinity in the Jordan Valley of Israel, the other in semi-arid Botswana where the herbaceous cover was estimated and mapped from aerial photographic survey. | ||||||
BibTeX:
@article{Oliver1990IJGIS,
author = {Oliver, M.A. and Webster, R.},
title = {Kriging: a method of interpolation for geographical information systems.},
journal = {International Journal of Geographical Information Science},
year = {1990},
volume = {4},
number = {3},
pages = {313-332},
doi = {10.1080/02693799008941549}
}
|
||||||
| Openshaw, S. | 1989 | Accuracy of Spatial Databases. [BibTeX] |
Taylor & Francis, London , 263-276 | GIS, uncertainty | ||
BibTeX:
@inbook{Openshaw1989inbook,
author = {Openshaw, S.},
title = {Accuracy of Spatial Databases.},
publisher = {Taylor \& Francis, London},
year = {1989},
pages = {263-276}
}
|
||||||
| Oppenheimer, M. | 1998 | Global warming and the stability of the West Antarctic Ice Sheet. | Nature 393 , 325-332 | ISM | DOI |
|
| Abstract: Of today’s great ice sheets, the West Antarctic Ice Sheet poses the most immediate threat of a large sea-level rise, owing to its potential instability. Complete release of its ice to the ocean would raise globalmean sea level by four to six metres, causing major coastal flooding worldwide. Human-induced climate change may play a significant role in controlling the long-term stability of the West Antarctic Ice Sheet and in determining its contribution to sea-level change in the near future. | ||||||
BibTeX:
@article{Oppenheimer1998Nature,
author = {Oppenheimer, Michael},
title = {Global warming and the stability of the {West Antarctic} Ice Sheet.},
journal = {Nature},
year = {1998},
volume = {393},
pages = {325-332},
doi = {10.1038/30661}
}
|
||||||
| Otto-Bliesner, B. L. | 1996 | Initiation of a continental ice sheet in a global climate model (GENESIS). [BibTeX] |
Journal of Geophysical Research 101 (D12) , 16909-16920 | ISM | ice sheet initiation; global climate model; GCM; GENESIS; inception; | |
BibTeX:
@article{Bliesner1996JGR,
author = {Otto-Bliesner, Bette L.},
title = {Initiation of a continental ice sheet in a global climate model {(GENESIS).}},
journal = {Journal of Geophysical Research},
year = {1996},
volume = {101},
number = {D12},
pages = {16909-16920}
}
|
||||||
| Otto-Bliesner, B. L., Brady, E. C., Clauzet, G., Tomas, R., Levis, S. & Kothavala, Z. | 2006 | Last Glacial Maximum and Holocene Climate in CCSM3. | Journal of Climate 19 (11) , 2526-2544 | DOI |
||
| Abstract: The climate sensitivity of the Community Climate System Model version 3 (CCSM3) is studied for two past climate forcings, the Last Glacial Maximum (LGM) and the mid-Holocene. The LGM, approximately 21 000 yr ago, is a glacial period with large changes in the greenhouse gases, sea level, and ice sheets. The mid-Holocene, approximately 6000 yr ago, occurred during the current interglacial with primary changes in the seasonal solar irradiance. The LGM CCSM3 simulation has a global cooling of 4.5°C compared to preindustrial (PI) conditions with amplification of this cooling at high latitudes and over the continental ice sheets present at LGM. Tropical sea surface temperature (SST) cools by 1.7°C and tropical land temperature cools by 2.6°C on average. Simulations with the CCSM3 slab ocean model suggest that about half of the global cooling is explained by the reduced LGM concentration of atmospheric CO2 (∼50% of present-day concentrations). There is an increase in the Antarctic Circumpolar Current and Antarctic Bottom Water formation, and with increased ocean stratification, somewhat weaker and much shallower North Atlantic Deep Water. The mid-Holocene CCSM3 simulation has a global, annual cooling of less than 0.1°C compared to the PI simulation. Much larger and significant changes occur regionally and seasonally, including a more intense northern African summer monsoon, reduced Arctic sea ice in all months, and weaker ENSO variability. |
||||||
BibTeX:
@article{Otto-Bliesner2006JC,
author = {Otto-Bliesner, Bette L. and Brady, Esther C. and Clauzet, Gabriel and Tomas, Robert and Levis, Samuel and Kothavala, Zav},
title = {Last Glacial Maximum and {Holocene} Climate in {CCSM3}.},
journal = {Journal of Climate},
year = {2006},
volume = {19},
number = {11},
pages = {2526-2544},
doi = {10.1175/JCLI3748.1}
}
|
||||||
| Paterson, W. | 1994 | The Physics of Glaciers. [BibTeX] |
Pergamon Press | ISM | ||
BibTeX:
@book{paterson1994book,
author = {Paterson, W.S.B.},
title = {The Physics of Glaciers.},
publisher = {Pergamon Press},
year = {1994},
edition = {3}
}
|
||||||
| Paterson, W. & Budd, W. | 1982 | Flow parameters for ice sheet modelling. [BibTeX] |
Cold Regions Science and Technology 6 (2) , 175-177 | ISM | data; ice sheet model; | DOI |
BibTeX:
@article{paterson1982crst,
author = {Paterson, W.S.B. and Budd, W.F.},
title = {Flow parameters for ice sheet modelling.},
journal = {Cold Regions Science and Technology},
year = {1982},
volume = {6},
number = {2},
pages = {175-177},
doi = {10.1016/0165-232X(82)90010-6}
}
|
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| Pattyn, F. | 2003 | Ice-sheet modelling at different spatial resolutions: focus on the grounding zone. | Annals of Glaciology 31 , 211-216 | ISM | ice sheet modelling, ice sheet / ice shelf interface, basal drag, longitudinal stress | |
| Abstract: A high resolution time-dependant two-dimensional flowline model was developed, which takes into account all relevant stresses (i.e. both shear and longitudinal stresses), and which is solved on a fixed finite-difference grid. Special attention was paid to the computational efficiency. A comparison is made with a smiliar model that solves the velocity field according to the shallow-ice approximation. Both models were applied to an East Antarctic flowline for which the data on surface and bedrock elevation were sampled at different spatial resolutions. The numerical analysis deals with the importance of longitudinal stresses at the ice sheet / ice shelf interface at different grid sizes, and the importance of basal drag versus driving stress in basal sliding laws. At a grid resolution of 5 to 10 km the force balance indicates that all stress components are of equal importance in an area that is larger than the nominal grid size. When sliding becomes dominant, this transition zone considerably widens. Furthermore, the longitudinal stress deviator is found to vary considerably with depth due to the thermomechanical coupling. | ||||||
BibTeX:
@article{pattyn2003agla,
author = {Pattyn, Frank},
title = {Ice-sheet modelling at different spatial resolutions: focus on the grounding zone.},
journal = {Annals of Glaciology},
year = {2003},
volume = {31},
pages = {211-216}
}
|
||||||
| Pattyn, F. | 2003 | A new three-dimensional higher-order thermomechanical ice sheet model: Basic sensitivity, ice stream development, and ice flow across subglacial lakes. [BibTeX] |
Journal of Geophysical Research - Solid Earth 108 (B8) , art.no.2382 | ISM | higher-order; ice sheet model; thermo-mechanical; icestream; subglacial lake; velocity fields; | URL |
BibTeX:
@article{pattyn2003jgr,
author = {Pattyn, Frank },
title = {A new three-dimensional higher-order thermomechanical ice sheet model: Basic sensitivity, ice stream development, and ice flow across subglacial lakes.},
journal = {Journal of Geophysical Research - Solid Earth},
year = {2003},
volume = {108},
number = {B8},
pages = {art.no.2382},
url = {http://homepages.vub.ac.be/~fpattyn/papers/jgr03.pdf}
}
|
||||||
| Payne, A. J. | 1999 | A thermomechanical model of ice flow in West Antarctica. | Climate Dynamics 15 , 115-125 | ISM | ice flow model; thermo-mechanical; ice stream; WAIS; Antarctica | DOI |
| Abstract: This study uses a three-dimensional thermo-mechanical model to investigate the internal flow dynamics of the West Antarctic Ice Sheet (WAIS). The model allows ice thickness, flow and temperature to interact freely. Its domain is prescribed as that of the present-day grounded WAIS. Realistic present-day climatic and topographical boundary conditions are employed. The analysis of a series of experiments pays particular attention to the location and dynamics of concentrations of ice flow (ice streams). Underlying topographic troughs are crucial in determining the strength and location of these concentrations of flow. The flow pattern generated by subglacial troughs is made more distinct by the inclusion of ice flow/temperature coupling. The inclusion of sliding leads to the generation of limit cycles in the ice flow. They are concentrated around the present-day ice streams B and C of the Siple Coast and have a period of 5 to 10 ky. There appears to be competition between several preferred ice flow pathways in this area. The two end members of the flow regime are a strong ice stream C with a weakened ice stream A/B complex, and strong ice streams A and B with a dormant ice stream C. Ice streams appear to require ice discharges above a certain threshold in order to maintain frictional heat generation and fast flow. Individual ice streams can therefore interact through changes in catchment-area size: a reduction in catchment area reduces the volume of ice entering a stream and can cause stagnation as the amount of frictional heating falls. | ||||||
BibTeX:
@article{payne1999cd,
author = {Payne, Antony J.},
title = {A thermomechanical model of ice flow in {West Antarctica.}},
journal = {Climate Dynamics},
year = {1999},
volume = {15},
pages = {115-125},
doi = {10.1007/s003820050271}
}
|
||||||
| Payne, A. J. | 1995 | Limit cycles in the basal thermal regime of ice sheets. | Journal of Geophysical Research 100 (B3) , 4249-4263 | URL |
||
| Abstract: This paper investigates the thermodynamic consequences of introducing basal sliding into a two-dimensional ice sheet model. The coupling of ice sheet form, flow field, and temperature evolution gives rise to limit cycles in the basal thermal regime of the ice sheet. Typical periods are 4000 to 5000 years and up to 45% of the ice sheet length can be affected. The limit cycles are caused by the switching on and off of sliding as basal ice reaches the pressure melting point. An analysis of the various heat fluxes at the ice sheet base stresses the roles of vertical diffusion and the heat generated by internal deformation and sliding in controlling the period and extent of the cycles. Limit cycles are found to persist in the face of various climatic (snow accumulation rate and air temperature) parameterizations, as well as for different basal sliding parameterizations. The types of oscillation change produced by varying accumulation rate is particularly interesting. Several distinct patterns of behavior are observed. For low accumulation rate ice sheets, a period of 6000–7000 years is dominant; for medium accumulation rate ice sheets, the 3000 to 4000 year period is dominant; while for larger accumulation rates, the oscillations become highly irregular with long (>10,000 years) periods. | ||||||
BibTeX:
@article{Payne1995JGR,
author = {Payne, Antony J.},
title = {Limit cycles in the basal thermal regime of ice sheets.},
journal = {Journal of Geophysical Research},
year = {1995},
volume = {100},
number = {B3},
pages = {4249-4263},
url = {http://www.agu.org/pubs/crossref/1995.../94JB02778.shtml}
}
|
||||||
| Payne, A. J. & Baldwin, D. | 2000 | Analysis of ice-flow instabilities identified in the EISMINT intercomparison exercise. [BibTeX] |
Annals of Glaciology 30 , 204-210 | ISM | glaciers; ice sheet model | |
BibTeX:
@article{payne2000agla,
author = {Payne, Antony J. and Baldwin, D.J.},
title = {Analysis of ice-flow instabilities identified in the EISMINT intercomparison exercise.},
journal = {Annals of Glaciology},
year = {2000},
volume = {30},
pages = {204-210}
}
|
||||||
| Payne, A. J. & Baldwin, D. | 1999 | Thermomechanical modelling of the Scandinavian ice sheet: implications for ice-stream formation. [BibTeX] |
Annals of Glaciology 28 , 83-89 | |||
BibTeX:
@article{Payne1999AGla,
author = {Payne, Anthony J. and Baldwin, D.J.},
title = {Thermomechanical modelling of the Scandinavian ice sheet: implications for ice-stream formation.},
journal = {Annals of Glaciology},
year = {1999},
volume = {28},
pages = {83-89}
}
|
||||||
| Payne, A. J. & Dongelmans, P. | 1997 | Self-organization in the thermomechanical flow of ice sheets. [BibTeX] |
Journal of Geophysical Research 102,B6 , 12219-12233 | ISM | ||
BibTeX:
@article{Payne1997JGR,
author = {Payne, Antony J. and Dongelmans, P.W.},
title = {Self-organization in the thermomechanical flow of ice sheets.},
journal = {Journal of Geophysical Research},
year = {1997},
volume = {102,B6},
pages = {12219-12233}
}
|
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| Payne, A. J., Huybrechts, P., Abe-Ouchi, A., Calov, R., Fastook, J., Greve, R., Marshall, S., Marsiat, I., Ritz, C., Tarasov, L. & Thomassen, M. | 2000 | Results from the EISMINT model intercomparaison: the effects of thermomechanical coupling. | Journal of Glaciology 46 (153) , 227-238 | ISM | EISMINT; model comparison; thermo-mechanical coupling | URL |
| Abstract: This paper discusses results from the Second Phase of the European Ice Sheet Modelling Initiative (EISMINT). It reports the intercomparison of ten operational ice sheet models and uses a series of experiments to examine the implications of thermomechanical coupling on model behaviour. A schematic, circular ice sheet is used in the work which investigates both steady states and the response to stepped changes in climate. The major finding is that the radial symmetry implied in the experimental design can, under certain circumstances, break down with the formation of distinct, regularly spaced spokes of cold ice which extended from the interior of the ice sheet outward to the surrounding zone of basal pressure melting. These features also manifest themselves in the thickness and velocity distributions predicted by the models. They appear to be a common feature to all of the models which took part in the intercomparison and may stem from interactions between ice temperature, flow and surface form. The exact nature of these features varies between models and their existence appears to be controlled by the overall thermal regime of the ice sheet. | ||||||
BibTeX:
@article{payne2000jgla,
author = {Payne, Antony J. and Huybrechts, Philippe and Abe-Ouchi, Ayako and Calov, R. and Fastook, J.L. and Greve, R. and Marshall, S.J. and Marsiat, I. and Ritz, C. and Tarasov, L. and Thomassen, M.P.A},
title = {Results from the {EISMINT} model intercomparaison: the effects of thermomechanical coupling.},
journal = {Journal of Glaciology},
year = {2000},
volume = {46},
number = {153},
pages = {227-238},
url = {http://www.ingentaconnect.com/content/igsoc/jog/2000/00000046/00000153/art00007}
}
|
||||||
| Payne, A. J. & Sugden, D. E. | 1990 | Climate and the initiation of maritime ice sheets. [BibTeX] |
Annals of Glaciology 14 , 232-237 | ISM | ||
BibTeX:
@article{payne1990agla,
author = {Payne, Antony J. and Sugden, David E.},
title = {Climate and the initiation of maritime ice sheets.},
journal = {Annals of Glaciology},
year = {1990},
volume = {14},
pages = {232-237}
}
|
||||||
| Payne, A. J. & Sugden, D. E. | 1990 | Topography and ice sheet growth. [BibTeX] |
Earth Surface Processes and Landforms 15 , 625-639 | ISM | ice sheets; loch lomond readvance; mass balance, numerical model | |
BibTeX:
@article{payne1990espl,
author = {Payne, Antony J. and Sugden, David E.},
title = {Topography and ice sheet growth.},
journal = {Earth Surface Processes and Landforms},
year = {1990},
volume = {15},
pages = {625-639}
}
|
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| Pellicciotti, F., Brock, B., Strasser, U., Burlando, P., Funk, M. & Corripio, J. | 2005 | An enhanced temperature-index glacier melt model including the shortwave radiation balance: development and testing for Haut Glacier d'Arolla, Switzerland. | Journal of Glaciology 51 (175) , 573-587 | URL |
||
| Abstract: An enhanced temperature-index glacier melt model, incorporating incoming shortwave radiation and albedo, is presented. The model is an attempt to combine the high temporal resolution and accuracy of physically based melt models with the lower data requirements and computational simplicity of empirical melt models, represented by the 'degree-day' method and its variants. The model is run with both measured and modelled radiation data, to test its applicability to glaciers with differing data availability. Five automatic weather stations were established on Haut Glacier d'Arolla, Switzerland, between May and September 2001. Reference surface melt rates were calculated using a physically based energy-balance melt model. The performance of the enhanced temperature-index model was tested at each of the four validation stations by comparing predicted hourly melt rates with reference melt rates. Predictions made with three other temperature-index models were evaluated in the same way for comparison. The enhanced temperature-index model offers significant improvements over the other temperature-index models, and accounts for 90-95% of the variation in the reference melt rate. The improvement is lower, but still significant, when the model is forced by modelled shortwave radiation data, thus offering a better alternative to existing models that require only temperature data input. | ||||||
BibTeX:
@article{Pellicciotti2005JGla,
author = {Pellicciotti, Francesca and Brock, Ben and Strasser, Ulrich and Burlando, Paolo and Funk, Martin and Corripio, Javier},
title = {An enhanced temperature-index glacier melt model including the shortwave radiation balance: development and testing for {Haut Glacier d'Arolla, Switzerland}.},
journal = {Journal of Glaciology},
year = {2005},
volume = {51},
number = {175},
pages = {573-587},
url = {http://www.ingentaconnect.com/content/igsoc/jog/2005/00000051/00000175/art00007?token=004d14775095582a2f3f58723375686f4957275c277b422c4067567d7634447b6e4a75056c033}
}
|
||||||
| Pike, R. J. | 2000 | Geomorphometry - diversity in quantitative surface analysis. | Progress in Physical Geography 24 (1) , 1-20 | DEM | DEM; topography; geomorphometry; geomorphology; landform quantification; surface form; terrain analysis; | URL |
| Abstract: A widening variety of applications is diversifying geomorphometry (digital terrain modelling), the quantitative study of topography. An amalgam of earth science, mathematics, engineering and computer science, the discipline has been revolutionized by the computer manipulation of gridded terrain heights, or digital elevation models (DEMs). Its rapid expansion continues. This article reviews the remarkable diversity of recent morphometric work in 15 selected topics and discusses their significance and prospects. The quantitative analysis of industrial microsurface topography is introduced to the earth science community. The 14 other topics are Internet access to geomorphometry; global DEMs; DEM modelling of channel networks; self-organized criticality; fractal and wavelet analysis; soil resources; landslide hazards; barchan dunes; harvesting wind energy; sea-ice surfaces; sea-floor abyssal hills; Japanese work in morphometry; and the emerging fields of landscape ecology and image understanding. Closing remarks note reasons for the diversity within geomorphometry, speculate on future trends and recommend creating a unified field of surface representation. | ||||||
BibTeX:
@article{Pike200PPG,
author = {Pike, Richard J.},
title = {Geomorphometry - diversity in quantitative surface analysis.},
journal = {Progress in Physical Geography},
year = {2000},
volume = {24},
number = {1},
pages = {1-20},
url = {http://www.ingentaconnect.com/content/arn/pipg/2000/00000024/00000001/art00001}
}
|
||||||
| Plewe, B. | 2002 | The Nature of Uncertainty in Historical Geographic Information. | Transactions in GIS 6 (4) , 431-456 | DOI |
||
| Abstract: While the presence of uncertainty in the geometric and attribute aspects of geographic information is well known, it is also present in temporal information. In spatiotemporal GIS databases and other formal representations, uncertainty in all three aspects of geography (space, time, and theme) must often be modeled, but a good data model must first be based on a sound theoretical understanding of spatiotemporal uncertainty. The nature of both uncertainty inherent in a phenomenon (often termed indeterminacy) and uncertainty in assertions of that phenomenon can be better understood through the Uncertain Temporal Entity Model, which characterizes the cause, type, and form of uncertainties in the spatial, temporal, and attribute aspects of geographic information. These uncertainties are the result of complexities and problems in two processes: the process of conceptualization, by which humans make sense of an infinitely complex reality, and measurement, by which we create formal representations (e.g. GIS) of those conceptual models of reality. Based on this framework, the nature and form of uncertainty is remarkably consistent across various situations, and is approximately equivalent in the three aspects, which will enable consistent solutions for representation and processing of spatiotemporal data. | ||||||
BibTeX:
@article{Plewe2002TIGIS,
author = {Plewe, Brandon},
title = {The Nature of Uncertainty in Historical Geographic Information.},
journal = {Transactions in GIS},
year = {2002},
volume = {6},
number = {4},
pages = {431-456},
doi = {10.1111/1467-9671.00121}
}
|
||||||
| Pollak, H. N. | 1982 | The head flow from the continents. | Annual Review of Earth and Planetary Sciences 10 , 459-481 | ISM | DOI |
|
| Abstract: The terrestrial heat flow is defined as the quantity of heat escaping per unit time from the Earth’s interior across each unit area of the Earth’s solid surface. The quantity varies from place to place over the surface of the Earth, as well as with time throughout Earth history. The total heat being lost from the Earth at a given time is the integral of the heat flow taken over the entire surface of earth. The heat flow from the continents is therefore but a part of the larger picture of global heat loss, indeed the lesser part whenc omparedto the heat loss through the floor of the ocean basins. (Pollack 1980, Sclater et al 1980, Davies 1980). This is so not only because of the lesser continental area, but also because of the generally smaller heat flow found on the continents than in the ocean basins. Thus, a full discussion of the thermal regime of the Earth and the mechanismsb y which it exhausts heat from the interior must center on the heat loss through the oceans, a topic which lies beyond the scope of this review. Nonetheless, because of the geological antiquity of at least some of their constituent terranes, the continents provide the only direct evidence about the thermal, tectonic, and petrologic processes of the Earth at times before the birth of any of the modemo cean basins somet wo hundred million years ago. Because inferences about earlier times are drawn wholly from materials now preserved in continents, one must be cautious not to overgeneralize about global tectonothermal processes from observations confined to continents. | ||||||
BibTeX:
@article{Pollak1982AREPS,
author = {Pollak, Henry N.},
title = {The head flow from the continents.},
journal = {Annual Review of Earth and Planetary Sciences},
year = {1982},
volume = {10},
pages = {459-481},
doi = {10.1146/annurev.ea.10.050182.002331}
}
|
||||||
| Pollard, D. | 1983 | A coupled climate-ice sheet model applied to the quaternary ice ages. [BibTeX] |
Journal of Geophysical Research - Oceans and Atmospheres 88 (NC12) , 7705-7718 | ISM | ||
BibTeX:
@article{pollard1983jgr,
author = {Pollard, David},
title = {A coupled climate-ice sheet model applied to the quaternary ice ages.},
journal = {Journal of Geophysical Research - Oceans and Atmospheres},
year = {1983},
volume = {88},
number = {NC12},
pages = {7705-7718}
}
|
||||||
| Pollard, D. | 1982 | A simple ice-sheet model yields realistic 100 kyr glacial cycles. | Nature 296 (5855) , 334-338 | ISM | DOI URL |
|
| Abstract: Records of global ice volume for the past 700 kyr, based on oxygen isotopic data from deep-sea cores and reflecting mainly the changing Northern Hemispheric ice sheets, show a dominant cycle of roughly 100 kyr period. The records also show smaller-amplitude oscillations with spectral peaks at roughly 40 and 20 kyr periods, which are well correlated with the Milankovich insolation variations due to perturbations in the Earth's orbital parameters. However, no model has accurately simulated the 100 kyr glacial cycle. Recently Birchfield et al.1 and Oerlemans2 have obtained encouraging agreement with some features of the glacial cycle by using a simple ice sheet model with a realistic time lag in the response of the bedrock to the ice load. This study extends their basic model, first by including topography to represent high ground in the north. Improved results can then be obtained but only with unrealistic parameter values and for some aspects of the record. Further improvements areobtained by crudely parameterizing possible calving at the equatorward ice sheet tip during deglaciation by proglacial lakes and/or marine incursions from the Atlantic, as emphasized by Andrews3. The resulting ice volume curves agree fairly well with the observed records and their power spectra over the past 700 kyr. | ||||||
BibTeX:
@article{pollard1982nature,
author = {Pollard, David},
title = {A simple ice-sheet model yields realistic 100 kyr glacial cycles.},
journal = {Nature},
year = {1982},
volume = {296},
number = {5855},
pages = {334-338},
url = {http://www.nature.com/nature/journal/v296/n5855/pdf/296334a0.pdf},
doi = {10.1038/296334a0}
}
|
||||||
| Pollard, D. | 1978 | Investigation of astronomical theory of ice ages using a simple climate ice sheet model. [BibTeX] |
Nature 272 (5650) , 233-235 | ISM | ||
BibTeX:
@article{pollard1978nature,
author = {Pollard, David},
title = {Investigation of astronomical theory of ice ages using a simple climate ice sheet model.},
journal = {Nature},
year = {1978},
volume = {272},
number = {5650},
pages = {233-235}
}
|
||||||
| Pollard, D. & DeConto, R. | 2007 | Grounding line behavior in a heuristically coupled ice sheet-shelf model. | Geophysical Research Abstracts | ISM | URL |
|
| Abstract: Standard equations for large-scale ice-sheet and ice-shelf flow are combined into one set, that includes grounded and floating regimes yet is numerically less expensive than full-stress models. The combination of the scaled equations is heuristic, but allows both horizontal shear and longitudinal stretching without a priori assumptions about the flow regime, and grounding lines are free to migrate. The equations are solved iteratively at each time step, and the type of flow depends primarily on bed type via the basal shear stress. The model is applied to basic aspects of grounding-line behavior, using idealized 1-D flowline geometries in which grounded inland ice flows into a marine ice shelf. Even in idealized cases, there are still fundamental unresolved issues regarding grounding-line sensitivity to sea-level change and bed properties, and the existence of multiple steady states. These and other issues are addressed in series of sensitivity tests, and results are discussed in the context of previous work and relevance to the West Antarctic Ice Sheet. | ||||||
BibTeX:
@inproceedings{Pollard2007EGU,
author = {Pollard, David and DeConto, R.M.},
title = {Grounding line behavior in a heuristically coupled ice sheet-shelf model.},
booktitle = {Geophysical Research Abstracts},
year = {2007},
volume = {9-03103},
url = {http://www.cosis.net/abstracts/EGU2007/03103/EGU2007-J-03103-1.pdf}
}
|
||||||
| Pollard, D. & DeConto, R. M. | 2003 | Antarctic ice and sediment flux in the Oligocene simulated by a climate-ice sheet-sediment model. | Palaeogeography, Palaeclimatology, Palaeoecology 198 , 53-67 | ISM | Antarctica; Ice sheets; Sediment budget; Oligocene; Paleoclimate; coupled model; climate model; sediment model; ice sheet model | |
| Abstract: A model of deforming sediment is added to a climate-ice sheet model, and applied to the Eocene-Oligocene transition in Antarctic ice volume around 34 Ma. The coupling between the global climate and ice sheet models is asynchronous, with a climate simulation performed once every 10 000 years, and only for the first 40 000 years. These global climate model solutions are re-used to perform runs of 400 000 years in length, with orbital forcing and different levels of CO2. The sediment model includes bulk transport under ice, generation of sub-ice till, and river transport, and predicts the continental-scale evolution of sediment thickness and coastal discharge. For the first few 10 000 s of years after the onset of substantial ice (triggered by CO2 falling below ~3x pre-industrial level), sediment discharge to the ocean is relatively uniform around the coast, derived from nearby pre-existing regolith. After that, most discharge is concentrated into ~4 sites at the mouths of major trough systems, with orbitally paced pulses on 104-yr scales. These sites and the average magnitudes of the fluxes agree generally with those deduced from offshore seismic and core data, although longer (10my) integrations are needed to model the real sediment evolution. | ||||||
BibTeX:
@article{pollard2003ppp,
author = {Pollard, David and DeConto, Robert M.},
title = {Antarctic ice and sediment flux in the Oligocene simulated by a climate-ice sheet-sediment model. },
journal = {Palaeogeography, Palaeclimatology, Palaeoecology},
year = {2003},
volume = {198},
pages = {53-67}
}
|
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| Pollard, D. & Thompson, S. L. | 1997 | Climate and ice-sheet mass balance at the last glacial maximum from the GENESIS version 2 global climate model. | Quaternary Science Reviews 16 (8) , 841-863 | DOI |
||
| Abstract: At the last glacial maximum (LGM) about 21,000 calendar years ago (21 ka BP), the overall mass balance of the Laurentide and Eurasian ice sheets should have been close to zero, since their rate of change of total ice volume was approximately zero at that time. The surface mass balance should have been zero or positive to balance any iceberg/iceshelf discharge and basal melting, but could not have been strongly negative. In principle, this can be tested by global climate model (CGM) simulations with prescribed ice-sheet extents and topography. We describe results from a suite of 21 ka BP simulations using a new global climate model (GENESIS version 2.0.a), with SSTs prescribed from CLIMAP (1981) and predicted by a mixed-layer ocean model, and with ice sheets prescribed from CLIh the ICE-4G (Peltier, 1994) and CLIMAP (1981) reconstructions. In common with previous GCM simulations using mixed-layer oceans, substantial cooling over and around Antarctica occurs due to ‘normal’ GCM dynamics and polar sea-ice feedback, without recourse to changes in thermohaline circulation. We find slightly enhanced cooling and cloudiness over low-latitude land masses compared to over ocean, especially over the Andes, which decreases the disagreement with land-based data and suggests that tropical CLIMAP SSTs may only be not, vert, similar1–2°C too warm. The GCM used here is well suited for ice-sheet mass-balance studies because (i) the surface can be represented at a finer resolution than the atmospheric GCM, (ii) an elevation correction accounts for spectral distortions of the atmospheric GCM topography, (iii) a simple post-processing correction for refreezing of meltwater is applied, and (iv) the model's precipitation and mass balances for present-day Greenland and Antarctica are realistic. However, for all reasonable combinations of SSTs and ice-sheet configurations, the predicted annual surface mass balances of the LGM Laurentide and Eurasian ice sheets are implausibly negative. Possible reasons for this discrepancy are discussed, including increased ice-age aerosols, higher CLIMAP-like ice-sheet profiles in the few thousand years preceding LGM, and a surge of the southern Laurentide just before LGM to fleetingly produce the ICE-4G profile at 21 ka BP. |
||||||
BibTeX:
@article{Pollard1997QSR,
author = {Pollard, David and Thompson, Starley L.},
title = {Climate and ice-sheet mass balance at the last glacial maximum from the GENESIS version 2 global climate model.},
journal = {Quaternary Science Reviews},
year = {1997},
volume = {16},
number = {8},
pages = {841-863},
doi = {10.1016/S0277-3791(96)00115-1}
}
|
||||||
| Purves, R., Clough, P. & Joho, H. | 2005 | Identifying imprecise regions for geographic information retrieval using the web. [BibTeX] |
Proceedings of the 13th GIS Research UK: GISRUK 2005 | GIS | URL |
|
BibTeX:
@inproceedings{Purves2005GISRUK,
author = {Purves, R.S. and Clough, Paul and Joho, Hideo},
title = {Identifying imprecise regions for geographic information retrieval using the web.},
booktitle = {Proceedings of the 13th GIS Research UK: GISRUK 2005},
year = {2005},
url = {http://www.dcs.gla.ac.uk/~hideo/pub/gisuk05/gisuk05.pdf}
}
|
||||||
| Purves, R. S. & Hebeler, F. | 2006 | An Introduction to GIS [BibTeX] |
Pearson | |||
BibTeX:
@inbook{purves2006introgis,
author = {Purves, Ross S. and Hebeler, Felix},
title = {An Introduction to GIS},
publisher = {Pearson},
year = {2006},
edition = {3}
}
|
||||||
| Purves, R. S. & Hulton, N. R. | 2000 | A climatic-scale precipitation model compared with the UKCP baseline climate. | International Journal of Climatology 20 , 1809-1821 | ISM | UK; downscaling; precipitation; UKCIP; palaeoclimate; orographic; model | DOI |
| Abstract: This paper describes a limited-area, reduced-process model of the large-scale physics of precipitation developed for predicting over climatic timescales. It represents an intermediate approach between a general circulation model (GCM) and full-physics model of precipitation at high resolutions. The model is designed for application in palaeoclimate modelling, specifically as input to ice-sheet models. The model is used to predict seasonal precipitation for the UK, using sea-surface temperatures, topography, mean wind speed and direction. Modelled data are compared with the United Kingdom Climate Impacts Programme (UKCIP) baseline climatologies for the UK and are shown, for westerly and southwesterly winds, to produce precipitation distributions and magnitudes which are in good agreement with the UKCIP data. The modelled data are much more spatially heterogeneous, reflecting the physical nature of the parameterization of the influence of orography. The model's sensitivity to temperature, wind speed and wind direction and its potential for driving ice-sheet models over long timescales are demonstrated. | ||||||
BibTeX:
@article{purves2000ijc,
author = {Purves, Ross S. and Hulton, Nicholas R.J.},
title = {A climatic-scale precipitation model compared with the {UKCP} baseline climate.},
journal = {International Journal of Climatology},
year = {2000},
volume = {20},
pages = {1809-1821},
doi = {10.1002/1097-0088(20001130)20:14<1809::AID-JOC587>3.0.CO;2-R}
}
|
||||||
| Purves, R. S. & Hulton, N. R. | 2000 | Experiments in linking regional climate, ice-sheet models and topography. | Journal of Quaternary Science 15 , 369-375 | ISM | ice-sheet models; regional climate models; coupled models; palaeoclimate | URL |
| Abstract: This paper describes the dynamic asynchronous coupling of an ice-sheet model with a climate model that calculates spatial atmospheric moisture flux. The coupled models are run over a hypothetical, symmetric topography for a range of different wind speeds and temperatures. Resultant ice-sheet profiles and distributions are compared with those from an ice-sheet model run with a constant, imposed climate. Ice sheets that develop under the dynamically linked models are shown to be asymmetric, with profiles extending up to 500 m lower on their windward side as a result of a strong positive mass-balance feedback. The feedback results from the imposition of the evolving ice-sheet topography on the atmospheric moisture transport. The experiments demonstrate the importance of using such a coupled model configuration in order to understand the processes that link ice sheets and climate, in particular in situations such as that of Patagonia, where a narrow mountain range lies athwart the prevailing wind. | ||||||
BibTeX:
@article{purves2000jqs,
author = {Purves, Ross S. and Hulton, Nicholas R.J.},
title = {Experiments in linking regional climate, ice-sheet models and topography.},
journal = {Journal of Quaternary Science},
year = {2000},
volume = {15},
pages = {369-375},
url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/72508320/PDFSTART}
}
|
||||||
| Purves, R. S., Mackaness, W. A. & Sugden, D. E. | 1999 | An approach to modelling the impact of snow drift on glaciation in the Cairngorm Mountains, Scotland. | Journal of Quaternary Science 14 (4) , 313-321 | ISM | Younger Dryas; Cairngorms; glaciation; snow drifting; GIS. | URL |
| Abstract: This paper uses a Geographical Information System (GIS) to develop a rule-based model of the effect of snow drifting on glacier growth in the Cairngorm Mountains, Scotland during the Younger Dryas interval. We develop a qualitative model of snow drift that uses a number of simple heuristics to generate a map of relative accumulation at a 50-m resolution over the massif. Relative susceptibility to snow drifting is then compared for a number of different zones under varying wind directions. We conclude that, under the conditions tested in our model, glaciation of the Cairngorms during the Younger Dryas was confined to the high corries and that the pattern of snow drifting suggested by our model points to dominant southerly winds. | ||||||
BibTeX:
@article{purves1999jqs,
author = {Purves, Ross S. and Mackaness, William A. and Sugden, David E.},
title = {An approach to modelling the impact of snow drift on glaciation in the Cairngorm Mountains, Scotland.},
journal = {Journal of Quaternary Science},
year = {1999},
volume = {14},
number = {4},
pages = {313-321},
url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/62501738/PDFSTART}
}
|
||||||
| Raaflaub, L. D. & Collins, M. J. | 2006 | The effect of error in gridded digital elevation models on the estimation of topographic parameters. | Environmental Modelling and Software 21 (5) , 710-732 | DEM, uncertainty | Digital elevation model; Topography; Error analysis | DOI |
| Abstract: Digital elevation models (DEMs) provide the basic information required to characterise the topographic attributes of terrain. The primary derived topographic parameters associated with DEMs are slope and aspect. Slope and aspect maps are used in a wide variety of applications. Slope and aspect can be used to calculate other significant topographic parameters such as upslope area and topographic index. The topographic index, in turn, can be used by distributed hydrological models to characterise the spatial distribution of terrain moisture. Many algorithms have been developed to calculate slope, aspect and upslope area from DEMs – specifically from gridded DEMs – but little work has gone into determining the uncertainty in these parameters, or the affect of this uncertainty in further applications. The accuracy of these parameters is dependent both on the algorithm and on the errors associated with the DEM itself. Since it is almost impossible to model all the errors associated with a given slope/aspect algorithm and since a DEM is normally only provided with a single rms error, simple error propagation is not adequate to determine the error associated with the derived topographic parameters. A more rigorous method of determining the affect of DEM errors on derived topographic parameters is with statistical analysis using Monte Carlo simulation and error realisations of the DEMs. In this research we demonstrate that the error sensitivity of slope decreases as the number of neighbours used in the algorithm increases, hence steepest neighbour algorithms, which are common in hydrology are more sensitive to DEM error than algorithms that use four or more neighbours. In contrast, the average error sensitivity of aspect to DEM error is not dependent on the algorithm used. However, while the mean variability of this sensitivity was lower for the steepest neighbour algorithms, their errors were spread over a greater variety of slopes while the eight neighbour algorithms had errors confined to flat regions. The error sensitivity of upslope area and topographic index is related to the use of steepest neighbour flow routing algorithm. | ||||||
BibTeX:
@article{Raaflaub2006EMS,
author = {Raaflaub, Lynn D. and Collins, Michael J.},
title = {The effect of error in gridded digital elevation models on the estimation of topographic parameters.},
journal = {Environmental Modelling and Software},
year = {2006},
volume = {21},
number = {5},
pages = {710-732},
doi = {10.1016/j.envsoft.2005.02.003}
}
|
||||||
| Rabus, B., Eineder, M., Roth, A. & Bamler, R. | 2003 | The shuttle radar topography mission�a new class of digital elevation models acquired by spaceborne radar. | Journal of Photogrammetry and Remote Sensing 57 (4) , 241-262 | DEM | Shuttle Radar Topography Mission (SRTM); synthetic aperture radar; interferometry; digital elevation models | DOI |
| Abstract: For 11 days in February 2000, the Shuttle Radar Topography Mission (SRTM) successfully recorded by interferometric synthetic aperture radar (InSAR) data of the entire land mass of the earth between 60°N and 57°S. The data acquired in C- and X-bands are processed into the first global digital elevation models (DEMs) at 1 arc sec resolution, by NASA-JPL and German aerospace center (DLR), respectively. From the perspective of the SRTM-X system, we give in this paper an overview of the mission and the DEM production, as well as an evaluation of the DEM product quality. Special emphasis is on challenges and peculiarities of the processing that arose from the unique design of the SRTM system, which has been the first single-pass interferometer in space. | ||||||
BibTeX:
@article{Rabus2003JPRS,
author = {Rabus, Bernhard and Eineder, Michael and Roth, Achim and Bamler, Richard},
title = {The shuttle radar topography mission�a new class of digital elevation models acquired by spaceborne radar.},
journal = {Journal of Photogrammetry and Remote Sensing},
year = {2003},
volume = {57},
number = {4},
pages = {241-262},
doi = {10.1016/S0924-2716(02)00124-7}
}
|
||||||
| Rana, S. & Wood, J. W. | 2000 | Weighted and metric surface networks - new insights and an interactive application for their generalisation in TCL/TK. | Working Paper (25) Centre for Advanced Spatial Analysis | uncertainty | URL |
|
| Abstract: The idea of characterising the different forms of natural topographic surfaces by a topological model based on their fundamental surface features has attracted many proposals. In this paper, a detailed discussion and new proposals on various issues related to the concept, generation, and visualisation of two graph theoretic based surface topology data structures – Weighted Surface Networks and their improved version, Metric Surface Networks - are presented. Also presented is an interactive Tcl/Tk application called Surface Topology Toolkit, which has been developed to support the discussion on aspects of their generalisation and visualisation. The highlight of the Surface Topology Toolkit is the utility to allow arbitrary contraction unlike the usual vertex importance based criterion. This paper proposes that effective automated surface topology modelling based on these surface networks requires (a) further research in the development of “computing� algorithms that will accurately locate critical surface points, be able to establish topological links, and also check topological consistency, (b) transforming their 2D straight line graph like appearance to 3D to improve visualisation and contraction, and (c) assessment and userawareness about the effects of each type of contraction criterion on the topography. | ||||||
BibTeX:
@techreport{rana2000workingpaper,
author = {Rana, Sanjay and Wood, Jospeh W.},
title = {Weighted and metric surface networks - new insights and an interactive application for their generalisation in TCL/TK.},
year = {2000},
number = {25},
url = {http://www.casa.ucl.ac.uk/surfacenetworks2.pdf}
}
|
||||||
| Raper, J. & Livingstone, D. | 1995 | Development of a geomorphological spatial model using object-oriented design. | International Journal of Geographical Information Science 9 (4) , 359-383 | DEM | DOI |
|
| Abstract: This paper argues that spatial modelling within the environmental sciences is not best achieved through the low level integration of environmental models and GIS (Geographical Information Systems), but by the creation of new integrated object-oriented modelling environments. In the light of this assertion the philosophical background to representation and spatio-temporal referencing are considered in order to outline the context for the design of OOgeomorph-an object-oriented spatial modelling system for geomorphology. The paper concludes with an example of the use of OOgeomorph to represent and test a coastal geomorphological theory. |
||||||
BibTeX:
@article{Raper1995IJGIS,
author = {Raper, Jonathan and Livingstone, David},
title = {Development of a geomorphological spatial model using object-oriented design.},
journal = {International Journal of Geographical Information Science},
year = {1995},
volume = {9},
number = {4},
pages = {359-383},
doi = {10.1080/02693799508902044}
}
|
||||||
| Reeh, N. | 1991 | Parameterization of melt rate and surface temperature on the Greenland ice sheet. [BibTeX] |
Polarforschung 59 (3) , 113-128 | ISM | ||
BibTeX:
@article{Reeh1991Polarforschung,
author = {Reeh, N.},
title = {Parameterization of melt rate and surface temperature on the {Greenland} ice sheet.},
journal = {Polarforschung},
year = {1991},
volume = {59},
number = {3},
pages = {113-128}
}
|
||||||
| Reinke, K. & Hunter, G. J. | 2002 | Spatial Data Quality. [BibTeX] |
Taylor & Francis, London , 76-101 | |||
BibTeX:
@inbook{Reinke2002inbook,
author = {Reinke, Karin and Hunter, Gary J.},
title = {Spatial Data Quality.},
publisher = {Taylor \& Francis, London},
year = {2002},
pages = {76-101}
}
|
||||||
| Reuter, H., Nelson, A. & Jarvis, A. | 2007 | An evaluation of void-filling interpolation methods for SRTM data. | International Journal of Geographical Information Science 21 (9) , 983-1008 | DEM | DEM; Interpolation methods; Void filling; DEM fusion | DOI |
| Abstract: The Digital Elevation Model that has been derived from the February 2000 Shuttle Radar Topography Mission (SRTM) has been one of the most important publicly available new spatial data sets in recent years. However, the 'finished' grade version of the data (also referred to as Version 2) still contains data voids (some 836,000 km2) - and other anomalies - that prevent immediate use in many applications. These voids can be filled using a range of interpolation algorithms in conjunction with other sources of elevation data, but there is little guidance on the most appropriate void-filling method. This paper describes: (i) a method to fill voids using a variety of interpolators, (ii) a method to determine the most appropriate void-filling algorithms using a classification of the voids based on their size and a typology of their surrounding terrain; and (iii) the classification of the most appropriate algorithm for each of the 3,339,913 voids in the SRTM data. Based on a sample of 1304 artificial but realistic voids across six terrain types and eight void size classes, we found that the choice of void-filling algorithm is dependent on both the size and terrain type of the void. Contrary to some previous findings, the best methods can be generalised as: kriging or inverse distance weighting interpolation for small and medium size voids in relatively flat low-lying areas; spline interpolation for small and medium-sized voids in high-altitude and dissected terrain; triangular irregular network or inverse distance weighting interpolation for large voids in very flat areas, and an advanced spline method (ANUDEM) for large voids in other terrains. | ||||||
BibTeX:
@article{Reuter2007IJGIS,
author = {Reuter, H.I. and Nelson, A. and Jarvis, A.},
title = {An evaluation of void-filling interpolation methods for SRTM data.},
journal = {International Journal of Geographical Information Science},
year = {2007},
volume = {21},
number = {9},
pages = {983-1008},
doi = {10.1080/13658810601169899}
}
|
||||||
| Rignot, E. & Thomas, R. H. | 2002 | Mass balance of polar ice sheets. | Science 297 (5586) , 1502-1506 | DOI |
||
| Abstract: Recent advances in the determination of the mass balance of polar ice sheets show that the Greenland Ice Sheet is losing mass by near-coastal thinning, and that the West Antarctic Ice Sheet, with thickening in the west and thinning in the north, is probably thinning overall. The mass imbalance of the East Antarctic Ice Sheet is likely to be small, but even its sign cannot yet be determined. Large sectors of ice in southeast Greenland, the Amundsen Sea Embayment of West Antarctica, and the Antarctic Peninsula are changing quite rapidly as a result of processes not yet understood. | ||||||
BibTeX:
@article{Rignot2002Science,
author = {Rignot, Eric and Thomas, Robert H.},
title = {Mass balance of polar ice sheets.},
journal = {Science},
year = {2002},
volume = {297},
number = {5586},
pages = {1502-1506},
doi = {10.1126/science.1073888}
}
|
||||||
| Ritz, C., Fabre, A. & Letréguilly, A. | 1997 | Sensitivity of a Greenland ice sheet model to ice flow and ablation parameters: consequences for the evolution through the last climatic cycle. | Climate Dynamics 13 (1) , 11-24 | ISM | ISM; climate model; | DOI |
| Abstract: Abstract. Sensitivity experiments are conducted to test the influence of poorly known model parameters on the simulation of the Greenland ice sheet by means of a three dimensional numerical model including the mechanical and thermal processes within the ice. Two types of experiments are performed: steady-state climatic conditions and simulations over the last climatic cycle with a climatic forcing derived from the GRIP record. The experiments show that the maximum altitude of the ice sheet depends on the ice flow parameters (deformation and sliding law coefficients, geothermal flux) and that it is low when the ice flow is fast. On the other hand, the maximum altitude is not sensitive to the ablation strength and consequently during the climatic cycle it is driven by changes in accumulation rate. The ice sheet extension shows the opposite sensitivity: it is barely affected by ice flow velocity and the ice covered area is smaller for large ablation coefficients. For colder climates, when there is no ablation, the ice sheet extension depends on the sea level. An interesting result is that the variations with time of the altitude at the ice divide (Summit) do not depend on the parameters we tested. The present modelled ice sheets resulting from the climatic cycle experiments are compared with the present measured ice sheet in order to find the set of parameters that gives the best fit between modelled and measured geometry. It seems that, compared to the parameter set most commonly used, higher ablation rate coefficents must be used. | ||||||
BibTeX:
@article{ritz1997cd,
author = {Ritz, Catherine and Fabre, Adeline and Letr\'{e}guilly, Anne},
title = {Sensitivity of a {Greenland} ice sheet model to ice flow and ablation parameters: consequences for the evolution through the last climatic cycle.},
journal = {Climate Dynamics},
year = {1997},
volume = {13},
number = {1},
pages = {11-24},
doi = {10.1007/s003820050149}
}
|
||||||
| Ritz, C., Mazauric, C., Peyaud, V. & Debreu, L. | 2007 | A mesh refinement approach, AGRIF, to take into account small scale processes in the GRISLI large scale ice sheet model. | Geophysical Research Abstracts | Subgrid | URL |
|
| Abstract: Recent observations indicate that the dynamics of outlet glaciers may affect the evolution of the whole ice sheet. Current ice sheets models are unable to take this impact into account because their grid is too coarse compared to outlet glaciers width. Futhermore, most of these models are based on the shallow ice approximation (SIA) and cannot transmit longitudinal stress perturbations that seems to be an essential process. GRISLI is a 3D thermomechanical ice sheet model. In addition to the usual shallow ice approximation for grounded ice flow, GRISLI incorporates ice streams that are treated as dragging ice shelves (MacAyeal, 1989). This feature allows the transmission of longitudinal stresses but the coarse grid is a major drawback to study the impact of outlets. Several methods can be used to account for interactions between small and large scales: finite elements method with irregular grid, nesting a small scale model inside the large scale one. We present here another alternative that is a mesh refinement approach. AGRIF is an adaptative mesh refinement software that can be used in any model provided it is discretized on a structured grid (cartesian or curvilinear). It makes possible to use an existing model on different grid levels while it manages interfaces between the grids and allows two-ways coupling. The mesh refinement is both spatial and temporal. Moreover, it also permit adaptative mesh refinement to automatically follow the physical processes. We present here the coupling method and preliminary results obtained by combining AGRIF and GRISLI. |
||||||
BibTeX:
@inproceedings{Ritz2007EGU,
author = {Ritz, Catherine and Mazauric, C. and Peyaud, V. and Debreu, L.},
title = {A mesh refinement approach, {AGRIF}, to take into account small scale processes in the {GRISLI} large scale ice sheet model.},
booktitle = {Geophysical Research Abstracts},
year = {2007},
volume = {9-09892},
url = {http://cosis.net/abstracts/EGU2007/09892/EGU2007-J-09892.pdf?PHPSESSID=7a04f9c770ead130f809e671d3f26551}
}
|
||||||
| Rodriguez, E., Morris, C. S. & Belz, J. E. | 2006 | A Global Assessment of the SRTM Performance | Photogrammetric Engineering and Remote Sensing 72 (3) , 249-260 | DEM | SRTM; accuracy; error; DEM; | URL |
| Abstract: The NASA/NGA Shuttle Radar Topography Mission (SRTM) collected interferometric radar data which has been used by the Jet Propulsion Laboratory to generate a near-global topography data product for latitudes smaller than 60°. One of the primary goals of the mission was to produce a data set that was globally consistent and with quantified errors. To achieve this goal, an extensive global ground campaign was conducted by NGA and NASA to collect ground truth that would allow for the global validation of this unique data set. This paper documents the results of this SRTM validation effort using this global data set. The table shown below summarizes our results (all quantities represent 90 percent errors in meters). Africa Australia EurasiaIslands N. America S. America Absolute Geolocation Error 11.9 7.2 8.8 9.0 12.6 9.0 Absolute Height Error 5.6 6.0 6.2 8.0 9.06.2 Relative Height Error 9.8 4.7 8.7 6.2 7.05.5 In the paper, we present a detailed description of how the results in this table were obtained. We also present detailed characterizations of the height and planimetric components of the error, their magnitudes, geographical distribution, and spatial structure. |
||||||
BibTeX:
@article{Rodriguez2006PERS,
author = {Rodriguez, Ernesto and Morris, Charles S. and Belz, J. Eric},
title = {A Global Assessment of the {SRTM} Performance},
journal = {Photogrammetric Engineering and Remote Sensing},
year = {2006},
volume = {72},
number = {3},
pages = {249-260},
url = {http://www.asprs.org/publications/pers/2006journal/march/abstracts.html}
}
|
||||||
| Rodriguez, E., Morris, C. S., Belz, J. E., Chapin, E. C., Martin, J. M., Daffer, W. & Hensle, S. | 2005 | An assessment of the SRTM topographic products. [BibTeX] |
Technical Report (JPL D-31639) Jet Propulsion Laboratory, Pasadena, California | DEM | URL |
|
BibTeX:
@techreport{Rodriguez2005srtm,
author = {Rodriguez, Ernesto and Morris, Charles S. and Belz, J. Eric and Chapin, E. C. and Martin, J. M. and Daffer, W. and Hensle, S.},
title = {An assessment of the {SRTM} topographic products.},
year = {2005},
number = {JPL D-31639},
url = {http://www2.jpl.nasa.gov/srtm/SRTM_D31639.pdf}
}
|
||||||
| Roe, G. H. & Lindzen, R. S. | 2001 | The Mutual Interaction between Continental-Scale Ice Sheets and Atmospheric Stationary Waves | Journal of Climate 14 , 1450-1465 | ISM | DOI |
|
| Abstract: The great continental ice sheets of the Pleistocene represented significant obstacles to the Northern Hemisphere midlatitude westerlies. They must therefore have forced large changes in the atmospheric circulation, and consequently also in the patterns of accumulation and melting over the ice sheets themselves. A simplified three-dimensional coupled ice sheet–stationary wave model is developed in order to understand the ice sheet’s response to the circulation changes that it induces. Consistent with ice age climate simulations, the ice sheet topography induces an anticyclonic circulation over the ice sheet, causing a slight warming over the western slopes and a stronger cooling over the remainder. The modeled feedbacks significantly affect the ice sheet configuration, with the most important influences being the patterns of summer temperature, and the topographically induced precipitation field. The time evolution of the ice sheet is also changed by the atmospheric feedbacks and the results suggest the possibility of multiple equilibrium solutions. | ||||||
BibTeX:
@article{Roe2001JC,
author = {Roe, Gerard H. and Lindzen, Richard S.},
title = {The Mutual Interaction between Continental-Scale Ice Sheets and Atmospheric Stationary Waves},
journal = {Journal of Climate},
year = {2001},
volume = {14},
pages = {1450-1465},
doi = {10.1175/1520-0442(2001)014<1450:TMIBCS>2.0.CO;2}
}
|
||||||
| Rutherford, J. | Analyzing Spatial Patterns of Error. Internet Ressource (Dan Brown) [BibTeX] |
uncertainty | URL |
|||
BibTeX:
@misc{Rutherford,
author = {Rutherford, James},
title = {Analyzing Spatial Patterns of Error. \emph{Internet Ressource (Dan Brown)}},
url = {http://www-personal.umich.edu/~danbrown/nre543/rutherfo.htm}
}
|
||||||
| Rutt, I. C., Hagdorn, M., Hulton, N. R. J. & Payne, A. J. | submitted | The `Glimmer’ community ice sheet model. | Journal of Geophysical Research | |||
| Abstract: We present a detailed description of the Glimmer ice sheet model, comprising the physics represented in the model and the numerical techniques used. Established methods are combined with good software design to yield an adaptable and widely-applicable model. A flexible framework for coupling Glimmer to global climate forcing is also described. Testing and benchmarking is of crucial importance if the outputs of numerical models are to be regarded as credible; we demonstrate that Glimmer performs very well against the well-known EISMINT benchmarks, and against other analytical solutions for ice flow. Glimmer therefore represents a well-founded and flexible frame work for the open-source development of ice sheet modelling. | ||||||
BibTeX:
@article{RuttsubmittedJGR,
author = {Rutt, Ian C. and Hagdorn, Magnus and Hulton, Nicholas R. J. and Payne, Anthony J.},
title = {{The `Glimmer’ community ice sheet model.}},
journal = {Journal of Geophysical Research},
year = {submitted}
}
|
||||||
| Saito, F., Abe-Ouchi, A. & Blatter, H. | 2006 | European Ice Sheet Modelling Initiative (EISMINT) model intercomparison experiments with first-order mechanics. | Journal of Geophysical Research 111 , F02012 | ISM | DOI |
|
| Abstract: The European Ice Sheet Modelling Initiative (EISMINT) intercomparison experiments with thermomechanical coupling are repeated with an ice sheet model that applies the first-order approximation for computing the flow field. The experiments impose radially symmetric boundary conditions. Most of the previous results have shown the loss of implied radial symmetry, i.e., the formation of distinct, regularly spaced spokes of cold ice in the simulated basal temperatures. A similar result is also observed in the presented first-order model results. The computed velocity components scatter widely along the marginal grid points. This indicates that the spokes may be triggered by the poor representation of the margin with a regular grid, where the steep gradients in the surface enhance the numerical errors. Additionally, the generally applied second-order discretization scheme tends to decouple even and odd numbered grid points, thus leading to wavy solutions with a wavelength of two grid cells. These patterns strongly suggest that the loss in radial symmetry is a numerical artifact. | ||||||
BibTeX:
@article{Saito2006JGR,
author = {Saito, Fuyuki and Abe-Ouchi, Ayako and Blatter, Heinz},
title = {European Ice Sheet Modelling Initiative {(EISMINT)} model intercomparison experiments with first-order mechanics.},
journal = {Journal of Geophysical Research},
year = {2006},
volume = {111},
pages = {F02012},
doi = {10.1029/2004JF000273}
}
|
||||||
| Saito, F., Abe-Ouchi, A. & Blatter, H. | 2003 | Effects of first-order stress gradients in an ice sheet evaluated by a three-dimensional thermomechanical coupled model. [BibTeX] |
Annals of Glaciology 37 (1) , 166-172 | ISM | DOI |
|
BibTeX:
@article{Saito2003AGla,
author = {Saito, Fuyuki and Abe-Ouchi, Ayako and Blatter, Heinz},
title = {Effects of first-order stress gradients in an ice sheet evaluated by a three-dimensional thermomechanical coupled model.},
journal = {Annals of Glaciology},
year = {2003},
volume = {37},
number = {1},
pages = {166-172},
doi = {10.3189/172756403781815645}
}
|
||||||
| Salzmann, N., Frei, C., Vidale, P. & Hoelzle, M. | 2007 | The application of Regional Climate Model output for the simulation of high-mountain permafrost scenarios. | Global and Planetary Change 56 , 188-202 | ISM | alpine permafrost; RCM; climate scenario; high-mountain area; complex topography | DOI |
| Abstract: This study investigates the possibilities and limitations of using Regional Climate Model (RCM) output for the simulation of alpine permafrost scenarios. It focuses on the general problem of scale mismatch between RCMs and impact models and, in particular, the special challenges that arise when driving an impact model in topographically complex high-mountain environments with the output of an RCM. Two approaches are introduced that take into account the special difficulties in such areas, and thus enable the use of RCM for alpine permafrost scenario modelling. Intended as an initial example, they are applied at the area of Corvatsch (Upper Engadine, Switzerland) in order to demonstrate and discuss the application of the two approaches, rather than to provide an assessment of future changes in permafrost occurrence. There are still many uncertainties and inaccuracies inherent in climate and impact models, which increase when driving one model with the output of the other. Nevertheless, our study shows that the use of RCMs offers new and promising perspectives for the simulation of high-mountain permafrost scenarios. |
||||||
BibTeX:
@article{Salzmann2007GPC,
author = {Salzmann, Nadine and Frei, Christoph and Vidale, Pier-Luigi and Hoelzle, Martin},
title = {The application of Regional Climate Model output for the simulation of high-mountain permafrost scenarios.},
journal = {Global and Planetary Change},
year = {2007},
volume = {56},
pages = {188-202},
doi = {10.1016/j.gloplacha.2006.07.006}
}
|
||||||
| Samet, H. | 1990 | The Design and Analysis of Spatial Data Structures. [BibTeX] |
Addison-Wesley, Reading, MA | |||
BibTeX:
@book{Samet1990book,
author = {Samet, H.},
title = {The Design and Analysis of Spatial Data Structures.},
publisher = {Addison-Wesley, Reading, MA},
year = {1990}
}
|
||||||
| Santos, J., Lodwick, W. A. & Neumaier, A. | 2002 | A New Approach to Incorporate Uncertainty in Terrain Modeling. | Geographic Information Science, Second International Conference Springer, Berlin | GIS | ||
| Review: A method for incorporating uncertainty in terrain modelling by expressing elevations as fuzzy numbers is proposed. Given a finite set of fuzzy elevations representative of the topographic surface in a certain region, we develop methods to construct surfaces that incorporate the uncertainty. The smoothness and continuity conditions of the surface generating method are maintained. Using this approach, we generalize some classic interpolators and compare them qualitatively. Extensions to wider classes of interpolators follow naturally from our approach. A numerical example is presented to illustrate this idea. |
||||||
BibTeX:
@incollection{Santos2002LNCS,
author = {Santos, Jorge and Lodwick, Weldon A. and Neumaier, Arnold},
title = {A New Approach to Incorporate Uncertainty in Terrain Modeling.},
booktitle = {Geographic Information Science, Second International Conference},
publisher = {Springer, Berlin},
year = {2002},
volume = {2478}
}
|
||||||
| Savvin, A., Greve, R., Calov, R., Mugge, B. & Hutter, K. | 2000 | Simulation of the Antarctic ice sheet with a three-dimensional polythermal ice-sheet model, in support of the EPICA project. II. Nested high-resolution treatment of Dronning Maud Land, Antarctica. [BibTeX] |
Annals of Glaciology 30 , 69-75 | ISM | ice sheet model; sub-grids; | |
BibTeX:
@article{savvin2000agla,
author = {Savvin, A. and Greve, R. and Calov, R. and Mugge, B. and Hutter, K.},
title = {Simulation of the Antarctic ice sheet with a three-dimensional polythermal ice-sheet model, in support of the EPICA project. II. Nested high-resolution treatment of Dronning Maud Land, Antarctica.},
journal = {Annals of Glaciology},
year = {2000},
volume = {30},
pages = {69-75}
}
|
||||||
| Schmidt, J., Evans, I. S. & Brinkmann, J. | 2003 | Comparison of polynomial models for land surface curvature calculation. | International Journal of Geographical Information Science 17 (8) , 797-814 | DEM | DOI |
|
| Abstract: Curvature is a fundamental surface property whose application, for example in geomorphology and hydrology, has long been recognised. Its measurement from Digital Terrain Models (DTMs) has received less attention than that of slope, and there is even disagreement about which definitions of curvature are most applicable. Here these problems are related to semantic problems in the definition of the land surface, and three distinct algorithms for the three main gravity-related components of curvature are compared for both artificial and real surfaces. Quadratic-based algorithms are shown to give more stable results. Higher-order local surfaces (e.g. partial quartic) can fit more complex landform features, but are reliable only for very accurate data. | ||||||
BibTeX:
@article{schmidt2003ijgis,
author = {Schmidt, Jochen and Evans, Ian S. and Brinkmann, Johannes},
title = {Comparison of polynomial models for land surface curvature calculation.},
journal = {International Journal of Geographical Information Science},
year = {2003},
volume = {17},
number = {8},
pages = {797-814},
doi = {10.1080/13658810310001596058}
}
|
||||||
| Schneeberger, C., Blatter, H., Abe-Ouchi, A. & Wild, M. | 2003 | Modelling changes in the mass balance of glaciers of the northern hemisphere for a transient 2x CO$_2$ scenario. | Journal of Hydrology 282 , 145-163 | ISM | Glacier; Climate Change; Mass balance; ice volume; mass balance model; flow model; GCM | DOI |
| Abstract: A climate forecast provided by a General Circulation Model (GCM), a glacier mass balance model and a glacier flow model is applied to a sample of 11 small glaciers. Another sample of six glaciers and six large, heavily glacierized areas in the arctic were modelled using only the climate forecast and the glacier mass balance model. The climate forecast of two different GCM s with identical experimental setup takes into account a gradual increase in atmospheric content ofCO2 and other greenhouse gases to a doubled CO2 equivalent in 2050 corresponding to the IPCC Scenario IS92a. The differences between the two GCM s are significant for the future development of the glacierization of arctic areas. The glacier mass balance model consists of a temperature index melt model, which uses potential direct clear sky radiation to obtain a better spatial and temporal resolution, combined with imposed snow precipitation. Static mass balance sensitivities span 20.2 to 21.5 mwe a21 8C, the higher and lower sensitivities apply for glaciers in more maritime and continental climates, respectively. All of the modelled glaciers and glacierized regions show a strong decrease in the net mass balance. Temperature changes dominate the effect of snow precipitation on the net mass balance. A temperature increase results in substantial increase in melt especially through the extension of the melt season in spring and fall. The mass balance projections for the sample of 11 glaciers are then used in a glacier flow model to simulate the dynamic reaction of the glacier to the changing climatic conditions. An iteration procedure accounts for possible feedback of changes in the glacier area and the ice surface elevation to the projected mass balance. For the modelled glaciers, an average volume loss of 60% until 2050 is predicted. Without the above iteration and assuming a constant glacier area, the volume change is overestimated by about 20%. A comparison with the climate predictions of the two different GCMs shows only a difference of about 10% in the mass loss obtained by flow modelling of four glaciers. | ||||||
BibTeX:
@article{schneeberger2003jh,
author = {Schneeberger, Christian and Blatter, Heinz and Abe-Ouchi, Ayako and Wild, Martin},
title = {Modelling changes in the mass balance of glaciers of the northern hemisphere for a transient 2x {CO$_2$} scenario.},
journal = {Journal of Hydrology},
year = {2003},
volume = {282},
pages = {145-163},
doi = {10.1016/S0022-1694(03)00260-9}
}
|
||||||
| Schneider, B. | 2001 | Phenomenon-based specification of the digital representation of terrain surfaces. | Transactions in GIS 5 (1) , 39-52 | DEM | DOI |
|
| Abstract: The phenomenon known as `terrain' is a continuous surface. However, when a digital terrain representation is based on a regular raster (i.e. a DEM) the digital surface is commonly not continuous. This is the case for the derivation of variables such as slope, aspect, and curvature values as performed in today's Geographic Information Systems (GIS). Often, there is no surface specified at all, as, for instance, when flow lines or watersheds are constructed. The discrepancy between the phenomenon to be modelled and its digital representation causes the terrain analysis results to be less accurate than they could be. Furthermore, if more than one type of terrain information is derived the results are likely to be based on different specifications of the seemingly same terrain surface. The combined application of the derivation results will likely introduce inconsistencies. This paper suggests founding the specification of digital terrain representations on a careful analysis of the properties of the phenomenon. The paper details the reasons for, and advantages of, continuous surface representations and emphasises the importance of a comprehensive documentation of the conceptual models underlying digital terrain representations. A review of suitable interpolation approaches for the specification of terrain surfaces is given. The paper discusses how the resulting digital surfaces are analysed and how measurement uncertainty may be accounted for. | ||||||
BibTeX:
@article{schneider2001aTIGIS,
author = {Schneider, Bernhard},
title = {Phenomenon-based specification of the digital representation of terrain surfaces.},
journal = {Transactions in GIS},
year = {2001},
volume = {5},
number = {1},
pages = {39-52},
doi = {10.1111/1467-9671.00066}
}
|
||||||
| Schneider, B. | 2001 | On the uncertainty of local form of lines and surfaces. | Cartography & Geographic Information Systems 28 (4) , 237-247 | uncertainty | SPATIAL MODELING; DIGITAL LINE AND SURFACE MODELS; UNCERTAINTY OF LOCAL SHAPE OF LINE AND SURFACE MOD; MODEL QUALITY; ABSTRACTION; INTERPOLATION; SCALE | |
| Abstract: Modeling line or surface phenomena digitally involves two tasks: discretization of the phenomenon, which yields a finite set of data, and subsequent interpolation, which reconstructs the continuum. Many mathematical techniques exist for the latter task, and most methods require a number of parameters to be specified. The shape of digital line or surface models between the data points (that is, the local shape) and the information derived from these models both depend on the selected method and, possibly, on the specification of parameters. The reconstruction of the continuum thus introduces uncertainty. This paper examines the sources and effects of this type of uncertainty. For this purpose, the modeling of lines and surfaces is separated into an abstraction, an implementation, and measurement. The individual factors affecting uncertainty of local shape in each step are identified and discussed. The paper concludes that local shape uncertainty, unlike positional uncertainty of given data, cannot be numerically assessed. Instead, measures of plausibility have to be used to denote the quality of digital models of lines and surfaces. Finally, the concept and potential problems of future empirical investigations are discussed. | ||||||
BibTeX:
@article{schneider2001cgis,
author = {Schneider, Bernhard},
title = {On the uncertainty of local form of lines and surfaces.},
journal = {Cartography \& Geographic Information Systems},
year = {2001},
volume = {28},
number = {4},
pages = {237-247}
}
|
||||||
| Schneider, B. | 1998 | Geomorphologically sound reconstruction of digital terrain surfaces from contours. | Proc. 8th Int. Symp. on Spatial Data Handling , 657-667 | DEM | Digital Terrain Modelling; Surface Reconstruction; Contour Lines | |
| Abstract: This paper presents a method to reconstruct a geomorphologically sound terrain surface representation from given contour lines. The term ‘geomorphologically sound’ is expressed by seven constraints digital terrain surfaces have to fulfil. The contour lines offer three levels of information: explicit and implicit information as well as so-called geomorphologic knowledge. These levels of information are exploited, firstly, to tessellate the area of interest and, secondly, to specify a continuous surface based on this subdivision. The tessellation is constructed by means of a Delaunay-triangulation which is terrain-specifically adjusted in order to reflect topographic structures as closely as possible. For this purpose, a method to extract structure lines from the contours has been developed. To specify the surface, Bézier-splines are chosen. The Clough-Tocher scheme allows for a C1-continuous surface representation. An iterative approach mutually calculating the paths of steepest descent, the normal vectors at each contour line point, and the triangular Bézier-patches ensures a geomorphologically sound terrain surface reconstruction. | ||||||
BibTeX:
@inproceedings{Schneider1998issdh,
author = {Schneider, Bernhard},
title = {Geomorphologically sound reconstruction of digital terrain surfaces from contours.},
booktitle = {Proc. 8th Int. Symp. on Spatial Data Handling},
year = {1998},
pages = {657-667}
}
|
||||||
| Schneider, B. & Martinoni, D. | 2001 | A Distributed Geoprocessing Concept for Enhancing Terrain Analysis for Environmental Modeling. | Transactions in GIS 5 (2) , 165-178 | DEM, uncertainty | DOI |
|
| Abstract: Geographic Information Systems (GIS) are well suited to support environmental modeling for dealing with space. However, some of the limitations of current GIS are the lack of tools for comprehensive documentation of the models, the inadequate representation of fields, and the deficient methodology for comprehensive management of uncertainty. Using Digital Terrain Modeling and Analysis as an example, this paper proposes an enhanced approach to overcome these drawbacks. It suggests implementing sophisticated functionality for modeling and analysis of fields in special-purpose modules outside monolithic GIS. These modules include three components: (1) an extensive framework for metainformation that allows a sound assessment of the fitness-for-use of digital field representations for environmental modeling applications, (2) an explicit digital representation of the field phenomenon equipped with the appropriate tools for the derivation of data, and (3) the methods to assess the quality of derived data. A standardized interface enables communication between the module and other software components. The presented modular approach combines the functionality of common GIS with highly specialized modeling and analysis tools encapsulating expert knowledge about the represented phenomena. | ||||||
BibTeX:
@article{Schneider2001bTIGIS,
author = {Schneider, Bernhard and Martinoni, Daria},
title = {A Distributed Geoprocessing Concept for Enhancing Terrain Analysis for Environmental Modeling.},
journal = {Transactions in GIS},
year = {2001},
volume = {5},
number = {2},
pages = {165-178},
doi = {10.1111/1467-9671.00074}
}
|
||||||
| Schoof, C. | 2007 | Marine ice-sheet dynamics. Part 1. The case of rapid sliding. | Journal of Fluid Mechanics 573 , 27-53 | ISM | DOI |
|
| Abstract: Marine ice sheets are continental ice masses resting on bedrock below sea level. Their dynamics are similar to those of land-based ice sheets except that they must couple with the surrounding floating ice shelves at the grounding line, where the ice reaches a critical flotation thickness. In order to predict the evolution of the grounding line as a free boundary, two boundary conditions are required for the diffusion equation describing the evolution of the grounded-ice thickness. By analogy with Stefan problems, one of these conditions imposes a prescribed ice thickness at the grounding line and arises from the fact that the ice becomes afloat. The other condition must be determined by coupling the ice sheet to the surrounding ice shelves. Here we employ matched asymptotic expansions to study the transition from ice-sheet to ice-shelf flow for the case of rapidly sliding ice sheets. Our principal results are that the ice flux at the grounding line in a two-dimensional ice sheet is an increasing function of the depth of the sea floor there, and that ice thicknesses at the groundingline must be small compared with ice thicknesses inland. These results indicate that marine ice sheets have a discrete set of steady surface profiles (if they have any at all) and that the stability of these steady profiles depends on the slope of the sea floor at the grounding line. |
||||||
BibTeX:
@article{Schoof2007JFM,
author = {Schoof, Christian},
title = {Marine ice-sheet dynamics. Part 1. The case of rapid sliding.},
journal = {Journal of Fluid Mechanics},
year = {2007},
volume = {573},
pages = {27-53},
doi = {10.1017/S0022112006003570}
}
|
||||||
| Schoof, C. | 2007 | Ice sheet grounding line dynamics: steady states, stability and hysteresis. | Journal of Geophysical Research 112 , F03S28 | ISM | DOI |
|
| Abstract: The ice sheet–ice shelf transition zone plays an important role in controlling marine ice sheet dynamics, as it determines the rate at which ice flows out of the grounded part of the ice sheet. Together with accumulation, this outflow is the main control on the mass balance of the grounded sheet. In this paper, we verify the results of a boundary layer theory for ice flux in the transition zone against numerical solutions that are able to resolve the transition zone. Very close agreement is obtained, and grid refinement in the transition zone is identified as a critical component in obtaining reliable numerical results. The boundary layer theory confirms that ice flux through the grounding line in a two-dimensional sheet-shelf system increases sharply with ice thickness at the grounding line. This result is then applied to the large-scale dynamics of a marine ice sheet. Our principal results are that (1) marine ice sheets do not exhibit neutral equilibrium but have well-defined, discrete equilibrium profiles; (2) steady grounding lines cannot be stable on reverse bed slopes; and (3) marine ice sheets with overdeepened beds can undergo hysteresis under variations in sea level, accumulation rate, basal slipperiness, and ice viscosity. This hysteretic behavior can in principle explain the retreat of the West Antarctic ice sheet following the Last Glacial Maximum and may play a role in the dynamics of Heinrich events. | ||||||
BibTeX:
@article{Schoof2007JGR,
author = {Schoof, Christian},
title = {Ice sheet grounding line dynamics: steady states, stability and hysteresis.},
journal = {Journal of Geophysical Research},
year = {2007},
volume = {112},
pages = {F03S28},
doi = {10.1029/2006JF000664}
}
|
||||||
| Schytt, D. | 1969 | A study of 'ablation gradient'. [BibTeX] |
Geografski Annaler 49A , 327-332 | ISM | ||
BibTeX:
@article{schytt1969ga,
author = {Schytt, D.E.},
title = {A study of 'ablation gradient'.},
journal = {Geografski Annaler},
year = {1969},
volume = {49A},
pages = {327-332}
}
|
||||||
| Shary, P. A. | 1995 | Land surface in gravity points classification [BibTeX] |
Mathematical Geology 27 (3) , 373-390 | DEM | DOI |
|
BibTeX:
@article{Shary1995MG,
author = {Shary, Peter A.},
title = {Land surface in gravity points classification},
journal = {Mathematical Geology},
year = {1995},
volume = {27},
number = {3},
pages = {373-390},
doi = {10.1007/BF02084608}
}
|
||||||
| Shary, P. A., Sharaya, L. S. & Mitusov, A. V. | 2002 | Fundamental quantitative methods of land surface analysis. | Geoderma 107 , 1-32 | DEM | Digital elevation model; Topography; Curvature; Scale; Invariant; Runoff | DOI |
| Abstract: Effective quantitative land surface analyses in soil science need scale-free land surface attributes (morphometric variables, MVs) to be introduced for making comparable results obtained at different scales. To investigate the problem in more detail, a conceptual scheme and curvatures studied earlier in Shary (1995) [Math. Geol. 27 (1995) 373] are further developed in this paper, formulae for a complete system of 12 curvatures and some other MVs are given, and modified Evans–Young algorithm for curvature calculation is described that does not emphasize grid directions. The conceptual scheme is based on that MVs often describe not the land surface itself, but rather the system “land surface+vector field�, where vector fields of common interest are gravitational field and solar irradiation. Correspondingly, morphometric variables and concepts may (1) refer to this system description (field-specific), or (2) be invariant with respect to any vector field (field-invariant), that is, describing the land surface itself, its geometrical form. From the other side, MVs and concepts may be (1) local, (2) regional, which need extended portions of a restricted part of land surface for their determination at a given point, or (3) global (planetary), when elevations of all the Earth are needed for their determination at a given point. Global MVs do not consist subject of this paper; so, the four classes of MVs are considered here: class A (local field-specific MVs), class B (regional field-specific), class C (local field-invariant), and class D (regional field-invariant). MVs of these classes permit description of geometrical land form, pre-requisits of surface runoff, thermal regime of slopes, and altitude zonality. Class A contains three independent MVs expressed by first derivatives of elevation Z by plan coordinates (slope steepness, slope direction, solar insolation) and seven curvatures expressed by second derivatives of Z; class C contains five curvatures; class B contains two variables (catchment and dispersal areas); MVs of class D are not introduced yet. Also, some non-system MVs of class A are described, sense of all MVs is described, and interrelationships between MVs are shown. Three curvatures are independent, not two, as this is often implied. It is experimentally shown that average depth of a depression defined in class B may not depend upon scale, while local MVs may not have limit values for large scales. Scale-free morphometric variables are defined here as those that have limit values for large scales. It is experimentally shown that maximal catchment area (class B) is a scale-free variable for thalwegs. These results show that local MVs are scale-specific (except elevation), but scale-free regional MVs might be introduced as a generalization of curvature concept. Two surface runoff accumulation mechanisms are considered in their relation to local and regional field-specific MVs; although the first one is generalized to a regional MV (catchment area), there is no regional MV for the second one description, although it is of great importance in soil science as describing slow profile changes. Geometrical forms were little studied in soil science; arguments are given that they may be useful for studying memory in soils, which is determined by temporal shifts between land surface formation and soil formation processes. The following topics are discussed: the current state of morphometry, an ambiguity in land form definitions, and a possibility to generalize curvature concept for regional scale-free MVs. The consideration is restricted by methods of the general geomorphometry; partial approaches are considered only by selection. | ||||||
BibTeX:
@article{Shary2002geoderma,
author = {Shary, Peter A. and Sharaya, Larisa S. and Mitusov, Andrew V.},
title = {Fundamental quantitative methods of land surface analysis.},
journal = {Geoderma},
year = {2002},
volume = {107},
pages = {1-32},
doi = {10.1016/S0016-7061(01)00136-7}
}
|
||||||
| Shortridge, A. M. | 2006 | Shuttle Radar Topography Mission elevation data error and its relationship to land cover. | Cartography and Geographic Information Science 33 (1) , 65-75 | DEM | DOI |
|
| Abstract: The Shuttle Radar Topography Mission (SRTM) has resulted in the construction of the first publicly available near-global high resolution digital elevation model (DEM). The utility of this DEM, as for any geospatial data set, is a function of its quality. This paper is concerned with the assessment of SRTM accuracy and its relationship to land cover. Two methods - one raster-based and one point-based - are compared to match "finished" three-arc-second SRTM data to high precision, high accuracy surveyed elevations, as well as a corresponding DEM from the USGS National Elevation Dataset (NED). Differences between the two methodologies were not found to be significant. Error for the study site is substantially less than the mission objective, but substantially more than that for the NED. Significant overestimation of actual elevations pervades the SRTM DEM, and the overestimation is significantly higher in forested areas. This systematic error has implications both for applications employing SRTM data and for research on elevation data error modeling. | ||||||
BibTeX:
@article{Shortridge2006CartGISc,
author = {Shortridge, Ashton M.},
title = {Shuttle Radar Topography Mission elevation data error and its relationship to land cover.},
journal = {Cartography and Geographic Information Science},
year = {2006},
volume = {33},
number = {1},
pages = {65-75},
doi = {10.1559/152304006777323172}
}
|
||||||
| Shortridge, A. M. | 2001 | Characterizing uncertainty in digital elevation models. [BibTeX] |
Spatial Uncertainty in Ecology: Implications for Remote Sensing and GIS Applications. Springer, Berlin, New York. , 238-257 | DEM | DEM ; uncertainty; | URL |
BibTeX:
@inproceedings{shortridge2001book,
author = {Shortridge, Ashton M.},
title = {Characterizing uncertainty in digital elevation models.},
booktitle = {Spatial Uncertainty in Ecology: Implications for Remote Sensing and GIS Applications.},
publisher = {Springer, Berlin, New York.},
year = {2001},
pages = {238-257},
url = {http://www.msu.edu/~ashton/pubs/chap11.pdf}
}
|
||||||
| Shortridge, A. M. & Clarke, K. C. | 1999 | On some limitations of square raster cell structures for digital elevation data modeling. | Spatial Accuracy Assessment: Land Information Uncertainty in Natural Resources. Ann Arbor Press, Michigan. | DEM | DEM ; uncertainty; raster;projection; spatial data model; spatial autocorrelation; | URL |
| Abstract: A range of geographic applications employ raster data structures in geographic information systems (GIS) for visualizing and analyzing digital elevation data. Reprojecting a raster-structured grid can introduce fundamental changes upon the data it contains. This chapter investigates the impact of these changes on commonly employed elevation data spaced at regular three arc second intervals. To account for these changes, a GIS employing a square raster structure must resample the elevation values, and either lose sampling density in one direction or over-densify in the other. This paper examines the implications of this projection distortion on statistical characteristics of the elevation surface and its derivatives. | ||||||
BibTeX:
@inproceedings{shortridge1999book,
author = {Shortridge, Ashton M. and Clarke, Keith C.},
title = {On some limitations of square raster cell structures for digital elevation data modeling.},
booktitle = {Spatial Accuracy Assessment: Land Information Uncertainty in Natural Resources.},
publisher = {Ann Arbor Press, Michigan.},
year = {1999},
url = {http://www.msu.edu/~ashton/pubs/rasterdem.pdf}
}
|
||||||
| Shortridge, A. M. & Goodchild, M. F. | 1999 | Communicating Uncertainty for Global Data Sets. | International Symposium on Spatial Data Quality. , 59-65 | uncertainty | URL |
|
| Abstract: This paper reviews the modeling approach to characterize spatial uncertainty and examines the prospects and challenges for developing statistically based uncertainty models for comprehensive global datasets like the Shuttle Radar Topography Mission (SRTM). Under this paradigm, data become integral inputs to models which characterize phenomena, rather than the primary representation of phenomena. One challenge is the identification of high quality, well distributed, high accuracy data necessary for developing the uncertainty model. A second challenge is distribution of the extensive processing for the simulation. A final challenge is producer and user acceptance of a new way of looking at the relationship between data and real-world spatial phenomena. How can geographic information science facilitate such a paradigm shift? | ||||||
BibTeX:
@inproceedings{Shortridge1999ISSDQ,
author = {Shortridge, Ashton M. and Goodchild, Michael F.},
title = {Communicating Uncertainty for Global Data Sets.},
booktitle = {International Symposium on Spatial Data Quality.},
year = {1999},
pages = {59-65},
url = {http://www.msu.edu/~ashton/pubs/global_uncert.pdf}
}
|
||||||
| Slater, J. A., Garvey, G., Johnston, C., Haase, J., Heady, B., Kroenung, G. & Little, J. | 2006 | The SRTM Data Finishing Process and Products. | Photogrammetric Engineering and Remote Sensing 72 (3) , 237-247 | DEM | SRTM; accuracy; processing;, topography; | URL |
| Abstract: The Shuttle Radar Topography Mission (SRTM) successfully acquired terrain elevation data for 80 percent of the Earth's landmass in February 2000. The radar system and data collection scheme designed by NASA's Jet Propulsion Laboratory (JPL) met the global requirements of the U.S. Department of Defense for Level 2 Digital Terrain Elevation Data (DTED®). JPL processed the raw data into unfinished DTED® 2 and other products that were delivered to two contractors of the National Geospatial-Intelligence Agency. The contractors edited the unfinished DTED® 2, updated the associated products, and generated finished products for distribution. Automated processes were developed by each contractor to identify, delineate and set heights for lakes, rivers, and ocean coastlines in conformance with an extensive set of editing rules created to maintain consistency and uniformity in the final products. The finished DTED® is significantly better than the 16 m vertical accuracy required by the original specification. | ||||||
BibTeX:
@article{Slater2006PERS,
author = {Slater, James A. and Garvey, Graham and Johnston, Carolyn and Haase, Jeffrey and Heady, Barry and Kroenung, George and Little, James},
title = {The SRTM Data Finishing Process and Products.},
journal = {Photogrammetric Engineering and Remote Sensing},
year = {2006},
volume = {72},
number = {3},
pages = {237-247},
url = {http://www.asprs.org/publications/pers/2006journal/march/abstracts.html}
}
|
||||||
| Slaymaker, O. & Kelly, R. E. | 2007 | The Cryosphere And Global Environmental Change [BibTeX] |
Blackwell Publishing, Oxford | ISM | ||
BibTeX:
@book{Slaymaker2007book,
author = {Slaymaker, Olav and Kelly, Richard E.J.},
title = {{The Cryosphere And Global Environmental Change}},
publisher = {Blackwell Publishing, Oxford},
year = {2007}
}
|
||||||
| Smith, M. J. & Clark, C. D. | 2005 | Methods for the visualization of digital elevation models for landform mapping | Earth Surface Processes and Landforms 30 (7) , 885-900 | DEM | DEM • lineament • landform • mapping • visualization | DOI |
| Abstract: Digital elevation models (DEMs) are increasingly used for landform mapping, particularly with the growing availability of national and global datasets. In this paper we describe a variety of techniques that can visualize a DEM. We then compare five techniques to ascertain which performs the most complete and unbiased visualization. We assess the visualization techniques by comparing landforms mapped from them against a detailed morphological map (derived from mapping of multi-azimuth relief-shaded DEMs cross-checked with stereo aerial photographs). Results show that no single visualization method provides complete and unbiased mapping. The relief-shaded visualizations are particularly prone to azimuth biasing, although they can highlight subtle landforms. We recommend curvature visualization for initial mapping as this provides a non-illuminated (and therefore unbiased) image. Initial mapping can then be supplemented with data from relief-shaded visualizations. | ||||||
BibTeX:
@article{Smith2005ESPL,
author = {Smith, Mike J. and Clark, Chris D.},
title = {Methods for the visualization of digital elevation models for landform mapping},
journal = {Earth Surface Processes and Landforms},
year = {2005},
volume = {30},
number = {7},
pages = {885-900},
doi = {10.1002/esp.1210}
}
|
||||||
| Smith, W. H. F. & Sandwell, D. T. | 1997 | Global Sea Floor Topography from Satellite Altimetry and Ship Depth Soundings. | Science 277 , 1956-1962 | DEM | DEM; ETOPO2 | |
| Abstract: A digital bathymetric map of the oceans with a horizontal resolution of 1 to 12 kilometers was derived by combining available depth soundings with high-resolution marine gravity information from the Geosat and ERS-1 spacecraft. Previous global bathymetric maps lacked features such as the 1600-kilometer-long Foundation Seamounts chain in the South Pacific. This map shows relations among the distributions of depth, sea floor area, and sea floor age that do not fit the predictions of deterministic models of subsidence due to lithosphere cooling but may be explained by a stochastic model in which randomly distributed reheating events warm the lithosphere and raise the ocean floor. | ||||||
BibTeX:
@article{smith1997science,
author = {Smith, Walter H. F. and Sandwell, David T.},
title = {Global Sea Floor Topography from Satellite Altimetry and Ship Depth Soundings.},
journal = {Science},
year = {1997},
volume = {277},
pages = {1956-1962}
}
|
||||||
| Stokes, C. R., Clark, C. D., Lian, O. B. & Tulaczyk, S. | 2007 | Ice stream sticky spots: A review of their identification and influence beneath contemporary and palaeo-ice streams. | Earth Science Reviews 81 (3-4) , 217-249 | ISM | ice sheet; ice stream; palaeo-ice stream; sticky spots | DOI |
| Abstract: Rapidly-flowing ice streams are the arterial drainage routes in continental ice sheets and exert a major influence on ice sheet mass balance. Recent observations have revealed that ice stream flow exhibits considerable variability, with relatively rapid changes taking place in speed and direction. This spatial and temporal variability is intimately linked to the conditions at the base of the ice streams and the distribution of localised patches of basal friction, known as 'sticky spots'. In this paper, we provide a detailed review of sticky spot observations from both contemporary and palaeo-ice stream beds in order to better understand their nature and influence. Observations and theoretical considerations reveal four primary causes of 'stickiness': (i), bedrock bumps; (ii), till-free areas; (iii), areas of 'strong' (well drained) till; and (iv), freeze-on of subglacial meltwater. These may act together in one location, or in isolation; and a progressive increase in their distribution could lead to ice stream shut-down. Bedrock bumps are influential under active ice streams, where they provide form drag and can create thinner ice which increases the likelihood of basal freeze-on. Increased bed roughness may prevent the lateral migration of some ice streams but bedrock bumps are unlikely to cause ice stream shut-down because, over long time-scales, ice stream erosion might be expected to reduce their amplitude. The influence of till-free areas beneath an ice stream will depend critically on the amount of water that might be drawn out of the surrounding till to lubricate such areas. They are likely to be most important in ice stream onset zones but their identification has proved difficult beneath active ice streams. If an ice stream operates solely by till deformation, it is conceivable that a progressive increase in the exposure of till-free areas could lead to shut-down through a process of sediment exhaustion. Areas of strong, well drained till have been identified beneath both active and ancient ice streams and are most likely to result from the reorganisation of subglacial meltwater. The collapse of an inefficient 'cannalised' system to a more efficient 'channelised' system can occur rapidly and this mechanism has been hypothesised as a candidate for ice stream shut-down in both contemporary and palaeo-settings. Basal freeze-on has also been observed and inferred from beneath modern and palaeo-ice streams, and a reduction in basal meltwater supply coupled with ice stream drawdown and the advection of cold ice increases the likelihood of switching off an ice stream. A paucity of data from ice stream sticky spots limits a better understanding of their nature, distribution and evolution beneath ice streams. Future technological advances are likely to improve the resolution of the data collected from the beds of modern ice streams but well-preserved palaeo-ice stream beds also hold potential for investigating their influence on ice stream flow and we present simple landsystems models to aid their identification. Such data will considerably enhance the basal boundary condition in ice stream models which will, ultimately, refine our predictions of the response of contemporary ice sheets to future changes in climate. | ||||||
BibTeX:
@article{Stokes2007ESR,
author = {Stokes, Chris R. and Clark, Chris D. and Lian, Olav B. and Tulaczyk, Slawek},
title = {Ice stream sticky spots: A review of their identification and influence beneath contemporary and palaeo-ice streams.},
journal = {Earth Science Reviews},
year = {2007},
volume = {81},
number = {3-4},
pages = {217-249},
doi = {10.1016/j.earscirev.2007.01.002}
}
|
||||||
| Stone, P. H. & Carlson, J. H. | 1979 | Atmospheric Lapse Rate Regimes and Their Parameterization. | Journal of Atmospheric Sciences 3 , 415-423 | Climate | URL |
|
| Abstract: Lapse rates, moist adiabatic lapse rates and the critical lapse rate for baroclinic adjustment are calculated and compared for the mean annual, January and July states in the Northern Hemisphere. In the troposphere above the planetary boundary layer zonal mean lapse rates are within 20% of the moist adiabatic lapse rate from the equator up to about 30°N in January and 50°N in July, but are appreciably more stable in higher latitudes. The latitudinal distribution of tropospheric mean lapse rates clearly delineates two regimes in the atmosphere: a low-latitude regime where the lapse rates are essentially moist adiabatic, and a high-latitude regime where the lapse rates are essentially the critical lapse rate for baroclinic adjustment. The dividing point between the two regimes shifts from 28°N in January to 47°N in July, and the transition is less sharp in July than in January. The absence of appreciable seasonal changes in lapse rates in midlatitudes can be attributed to counterbalancing seasonal changes in the strength of moist convection and baroclinic eddies. Hemispheric mean lapse rates in the mid and lower troposphere are within 0.4 K km-1 of the moist adiabatic lapse rate in July, but are as much as 1.9 K km-1 less in January. Implications for simple climate models are discussed. A principal conclusion is that the vertical temperature structure could be well approximated by a radiative-convective equilibrium model with two critical lapse rates: the moist adiabatic lapse rate and the critical lapse rate for baroclinic adjustment. | ||||||
BibTeX:
@article{Stone1979JAS,
author = {Stone, Peter H. and Carlson, John H.},
title = {Atmospheric Lapse Rate Regimes and Their Parameterization.},
journal = {Journal of Atmospheric Sciences},
year = {1979},
volume = {3},
pages = {415-423},
url = {http://ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175%2F1520-0469(1979)036%3C0415:ALRRAT%3E2.0.CO%3B2}
}
|
||||||
| Strahler, A. N. | 1952 | Hypsometric (area-altitude curve) analysis of erosional topography [BibTeX] |
Bulletin of the Geological Society of America 63 (11) , 1117-1141 | DEM | hydrology; geomorphology; DEM; geomorphometrics | |
BibTeX:
@article{strahler1952bgsa,
author = {Strahler, A. N.},
title = {Hypsometric (area-altitude curve) analysis of erosional topography},
journal = {Bulletin of the Geological Society of America},
year = {1952},
volume = {63},
number = {11},
pages = {1117-1141}
}
|
||||||
| Strasser, U., Corripio, J., Pellicciotti, F. & Burlando, P. | 2004 | Spatial and temporal variability of meteorological variables at Haut Glacier d'Arolla (Switzerland) during the ablation season 2001: Measurements and simulations. | Journal of Geophysical Research 109 , D03103 | ISM | DOI |
|
| Abstract: During the ablation period 2001 a glaciometeorological experiment was carried out on Haut Glacier d'Arolla, Switzerland. Five meteorological stations were installed on the glacier, and one permanent automatic weather station in the glacier foreland. The altitudes of the stations ranged between 2500 and 3000 m a.s.l., and they were in operation from end of May to beginning of September 2001. The spatial arrangement of the stations and temporal duration of the measurements generated a unique data set enabling the analysis of the spatial and temporal variability of the meteorological variables across an alpine glacier. All measurements were taken at a nominal height of 2 m, and hourly averages were derived for the analysis. The wind regime was dominated by the glacier wind (mean value 2.8 m s−1) but due to erosion by the synoptic gradient wind, occasionally the wind would blow up the valley. A slight decrease in mean 2 m air temperatures with altitude was found, however the 2 m air temperature gradient varied greatly and frequently changed its sign. Mean relative humidity was 71% and exhibited limited spatial variation. Mean incoming shortwave radiation and albedo both generally increased with elevation. The different components of shortwave radiation are quantified with a parameterization scheme. Resulting spatial variations are mainly due to horizon obstruction and reflections from surrounding slopes, i.e., topography. The effect of clouds accounts for a loss of 30% of the extraterrestrial flux. Albedos derived from a Landsat TM image of 30 July show remarkably constant values, in the range 0.49 to 0.50, across snow covered parts of the glacier, while albedo is highly spatially variable below the zone of continuous snow cover. These results are verified with ground measurements and compared with parameterized albedo. Mean longwave radiative fluxes decreased with elevation due to lower air temperatures and the effect of upper hemisphere slopes. It is shown through parameterization that this effect would even be more pronounced without the effect of clouds. Results are discussed with respect to a similar study which has been carried out on Pasterze Glacier (Austria). The presented algorithms for interpolating, parameterizing and simulating variables and parameters in alpine regions are integrated in the software package AMUNDSEN which is freely available to be adapted and further developed by the community. | ||||||
BibTeX:
@article{Strasser2004JGR,
author = {Strasser, Ulrich and Corripio, Javier and Pellicciotti, Francesca and Burlando, Paolo},
title = {Spatial and temporal variability of meteorological variables at {Haut Glacier d'Arolla (Switzerland)} during the ablation season 2001: Measurements and simulations.},
journal = {Journal of Geophysical Research},
year = {2004},
volume = {109},
pages = {D03103},
doi = {10.1029/2003JD003973}
}
|
||||||
| Strasser, U. & Etchevers, P. | 2003 | Using subgrid parameterization for topography and a forest canopy climate model for improving snowmelt flood simulations. | Climatology and Hydrology of Mountain Areas. John Wiley & Sons, Inc., Chichester | ISM | Daily discharge, spring flood, snowmelt, subgrid parameterization, topography, forest climate, flood forecast, SAFRAN, ISBA, CROCUS, Durance | DOI URL |
| Abstract: This study describes the application of the coupled models SAFRAN (meteorological variables), ISBA (soil-vegetation-atmosphere transfer) and CROCUS (snow cover evolution) to simulate daily discharges for the upper Durance catchment (French Alps) from 1981 to 1994. The results are validated by comparison with measurements at three gauging stations located in the watershed. Previous investigations have shown a remarkable overestimation of the spring flood peak generated by the modeled snowmelt. Significant improvements are achieved by increasing the model resolution from 8 km to 1 km, thus considering the elevation dependent snowmelt process more precisely. However, it is also possible to use subgrid parameterization techniques at the coarse grid resolution to improve simulation results while maintaining reasonable computational requirements. In this study, a statistically derived subgrid parameterization for topography, as well as a new subgrid parameterization for the climate in a forest canopy and its effect on the snow cover evolution are applied. Results show a significant improvement in the simulations, in particular for the combination of the two methods: the overestimation of the spring flood peak is reduced from 45.3 % to 27.5 %, 29.2 % and 14.1 %, respectively. The Nash-Sutcliffe efficiency of simulated daily discharges is improved from 0.73 (original experiment with 8 km resolution) to 0.77 (subgrid topography), to 0.75 (forest) and to 0.78 (combination of subgrid topography and forest). | ||||||
BibTeX:
@incollection{strasser2003in_dejong,
author = {Strasser, Ulrich and Etchevers, P.},
title = {Using subgrid parameterization for topography and a forest canopy climate model for improving snowmelt flood simulations. },
booktitle = {Climatology and Hydrology of Mountain Areas. },
publisher = {John Wiley \& Sons, Inc., Chichester},
year = {2003},
url = {http://www.geografie.uni-muenchen.de/Internetseiten/Mitarbeiter/Lehrpersonal/Strasser/artikel/Strasser_Etchevers.zip},
doi = {10.1002/0470858249.ch4}
}
|
||||||
| Sugden, D. E. | 1996 | The East Antarctic Ice Sheet: unstable ice or unstable ideas? [BibTeX] |
Transactions of the Institute of British Geographers 21 (3) , 443-454 | ISM | Antarctica; geomorphology; landscape evolution; ice sheet; mountains; | URL |
BibTeX:
@article{sugden1996tibg,
author = {Sugden, David E.},
title = {The East Antarctic Ice Sheet: unstable ice or unstable ideas?},
journal = {Transactions of the Institute of British Geographers},
year = {1996},
volume = {21},
number = {3},
pages = {443-454},
url = {http://www.jstor.org/view/00202754/ap020116/02a00010/0?frame=noframe&userID=823cb0a8@unizh.ch/01cce4403500501c12851&dpi=3&config=jstor}
}
|
||||||
| Sugden, D. E. & al. | The last glacial/interglacial transition in the southern Andes and migration of the westerlies. NERC grant proposal. [BibTeX] |
ISM | ||||
BibTeX:
@misc{sugden_grantproposal,
author = {Sugden, David E. and al.},
title = {The last glacial/interglacial transition in the southern Andes and migration of the westerlies. \emph{NERC grant proposal}.}
}
|
||||||
| Sugden, D. E., Hulton, N. R. & Purves, R. S. | 2002 | Modelling the inception of the Patagonian icesheet. | Quaternary International 95 96 , 55-64 | ISM | URL |
|
| Abstract: We use a coupled climate/icesheet model to simulate the inception and growth of the Patagonian icesheet. Assuming a temperature lowering of 61C and a uniform pressure gradient driving wind elds, an icesheet builds up with dimensions and morphology similar to that of the Last Glacial Maximum. Analysis of the stages of growth reveals the following conclusions. Different sectors of the 1800km long icesheet behave differently as a result of latitudinal variations in mass balance; the fastest growth occurs in latitudes 45 521S where the North and South Patagonian Ice elds merge and expand to the coast within 1500 model years. The most favourable topography for glacier initiation is the presence of high-elevation basins. Low-elevation summits in the mountain chain take a long time to become covered by ice because of the delay in ice spreading along the main mountain axis. Feedback between the increasing elevation of the icesheet and increasing mass balance on its windward ank enhances the rate of migration of the icesheet towards the precipitation source. There is a lee-side effect whereby easterly mountains are glaciated early on but are then starved of snow as ice builds up to the windward. Such locations should hold an empirical record of the early stages of a glacial cycle. | ||||||
BibTeX:
@article{sugden2002qi,
author = {Sugden, David E. and Hulton, Nicholas R.J. and Purves, Ross S.},
title = {Modelling the inception of the {Patagonian} icesheet.},
journal = {Quaternary International},
year = {2002},
volume = {95 96},
pages = {55-64},
url = {http://www.glaciologia.cl/textos/sugden.pdf}
}
|
||||||
| Sugden, D. E. & John, B. S. | 1976 | Glaciers and landscape: a geomorphological approach. [BibTeX] |
Arnold, London | ISM | ||
BibTeX:
@book{sugden1976book,
author = {Sugden, David E. and John, Brian Stephen},
title = {Glaciers and landscape: a geomorphological approach.},
publisher = {Arnold, London},
year = {1976}
}
|
||||||
| Sun, G., Ranson, K. J., Kharuk, V. I. & Kovacs, K. | 2003 | Validation of surface height from shuttle radar topography mission using shuttle laser altimeter. | Remote Sensing of Environment 88 (4) , 401-411 | DEM | DOI |
|
| Abstract: Spaceborne Interferometric SAR (InSAR) technology used in the Shuttle Radar Topography Mission (SRTM) and spaceborne lidar such as Shuttle Laser Altimeter-02 (SLA-02) are two promising technologies for providing global scale digital elevation models (DEMs). Each type of these systems has limitations that affect the accuracy or extent of coverage. These systems are complementary in developing DEM data. In this study, surface height measured independently by SRTM and SLA-02 was cross-validated. SLA data was first verified by field observations, and examinations of individual lidar waveforms. The geolocation accuracy of the SLA height data sets was examined by checking the correlation between the SLA surface height with SRTM height at 90 m resolution, while shifting the SLA ground track within its specified horizontal errors. It was found that the heights from the two instruments were highly correlated along the SLA ground track, and shifting the positions did not improve the correlation significantly. Absolute surface heights from SRTM and SLA referenced to the same horizontal and vertical datum (World Geodetic System (WGS) 84 Ellipsoid) were compared. The effects of forest cover and surface slope on the height difference were also examined. After removing the forest effect on SRTM height, the mean height difference with SLA-02 was near zero. It can be further inferred from the standard deviation of the height differences that the absolute accuracy of SRTM height at low vegetation area is better than the SRTM mission specifications (16 m). The SRTM height bias caused by forest cover needs to be further examined using future spaceborne lidar (e.g. GLAS) data. | ||||||
BibTeX:
@article{Sun2003RSE,
author = {Sun, G. and Ranson, K. J. and Kharuk, V. I. and Kovacs, K.},
title = {Validation of surface height from shuttle radar topography mission using shuttle laser altimeter.},
journal = {Remote Sensing of Environment},
year = {2003},
volume = {88},
number = {4},
pages = {401-411},
doi = {10.1016/j.rse.2003.09.001}
}
|
||||||
| Svendsen, J. I., Alexanderson, H., Astakhov, V. I., Demidov, I., Dowdeswell, J. A., Funder, S., Gataullin, V., Henriksen, M., Hjort, C., Houmark-Nielsen, M., Hubberten, H. W., Ingolfsson, O., Jakobsson, M., Kjaer, K. H., Larsen, E., Lokrantz, H., Lunkka, J. P., Lysa, A., Mangerud, J., Matiouchkov, A., Murray, A., Moller, P., Niessen, F., Nikolskaya, O., Polyak, L., Saarnisto, M., Siegert, C., Siegert, M. J., Spielhagen, R. F. & Stein, R. | 2004 | Late Quaternary ice sheet history of northern Eurasia. | Quaternary Science Reviews 23 (11-13) , 1229-1271 | ISM | DOI |
|
| Abstract: The maximum limits of the Eurasian ice sheets during four glaciations have been reconstructed: (1) the Late Saalian (>140 ka), (2) the Early Weichselian (100-80 ka), (3) the Middle Weichselian (60-50 ka) and (4) the Late Weichselian (25-15 ka). The reconstructed ice limits are based on satellite data and aerial photographs combined with geological field investigations in Russia and Siberia, and with marine seismic- and sediment core data. The Barents-Kara Ice Sheet got progressively smaller during each glaciation, whereas the dimensions of the Scandinavian Ice Sheet increased. During the last Ice Age the Barents-Kara Ice Sheet attained its maximum size as early as 90-80,000 years ago when the ice front reached far onto the continent. A regrowth of the ice sheets occurred during the early Middle Weichselian, culminating about 60-50,000 years ago. During the Late Weichselian the Barents-Kara Ice Sheet did not reach the mainland east of the Kanin Peninsula, with the exception of the NW fringe of Taimyr. A numerical ice-sheet model, forced by global sea level and solar changes, was run through the full Weichselian glacial cycle. The modeling results are roughly compatible with the geological record of ice growth, but the model underpredicts the glaciations in the Eurasian Arctic during the Early and Middle Weichselian. One reason for this is that the climate in the Eurasian Arctic was not as dry then as during the Late Weichselian glacial maximum. | ||||||
BibTeX:
@article{Svendsen2004QSR,
author = {Svendsen, John Inge and Alexanderson, Helena and Astakhov, Valery I. and Demidov, Igor and Dowdeswell, Julian A. and Funder, Svend and Gataullin, Valery and Henriksen, Mona and Hjort, Christian and Houmark-Nielsen, Michael and Hubberten, Hans W. and Ingolfsson, Olafur and Jakobsson, Martin and Kjaer, Kurt H. and Larsen, Eiliv and Lokrantz, Hanna and Lunkka, Juha Pekka and Lysa, Astrid and Mangerud, Jan and Matiouchkov, Alexei and Murray, Andrew and Moller, Per and Niessen, Frank and Nikolskaya, Olga and Polyak, Leonid and Saarnisto, Matti and Siegert, Christine and Siegert, Martin J. and Spielhagen, Robert F. and Stein, Ruediger},
title = {Late {Quaternary} ice sheet history of northern {Eurasia}.},
journal = {Quaternary Science Reviews},
year = {2004},
volume = {23},
number = {11-13},
pages = {1229-1271},
doi = {10.1016/j.quascirev.2003.12.008}
}
|
||||||
| Swisstopo | 2007 | DTM-AV 2m Grid [BibTeX] |
GIS | |||
BibTeX:
@misc{Swisstopo2007DTMAV,
author = {Swisstopo},
title = {{DTM-AV 2m Grid}},
year = {2007}
}
|
||||||
| Takatsuka, M. & Gahegan, M. | 2002 | GeoVISTA Studio: a codeless visual programming environment for geoscientific data analysis and visualization. | Computers & Geoscience 28 , 1131-1144 | GIS | Visual programming; Exploratory data analysis (EDA); Knowledge construction; Java; Component-oriented programming (COP) | URL |
| Abstract: The fundamentalgoalof the GeoVISTA Studio project is to improve geoscienti c analysis by providing an environment that operationally integrates a wide range of analysis activities, including those both computationally and visually based. Improving the infrastructure used in analysis has far-reaching potential to better integrate human-based and computationally based expertise, and so ultimately improve scienti c outcomes. To address these challenges, some dif cult system design and software engineering problems must be overcome. This paper illustrates the design of a component-oriented system, GeoVISTA Studio, as a means to overcome such dif culties by using state-of-the-art component-based software engineering techniques. Advantages described include: ease of program construction (visualprogramming), an open (non-proprietary) architecture, simple component-based integration and advanced deployment methods. This versatility has the potential to change the nature of systems development for the geosciences, providing better mechanisms to coordinate complex functionality, and as a consequence, to improve analysis by closer integration of software tools and better engagement of the human expert. Two example applications are presented to illustrate the potential of the Studio environment for exploring and better understanding large, complex geographical datasets and for supporting complex visual and computational analysis. | ||||||
BibTeX:
@article{takatsuka2002cg,
author = {Takatsuka, M. and Gahegan, M.},
title = {GeoVISTA Studio: a codeless visual programming environment for geoscientific data analysis and visualization.},
journal = {Computers \& Geoscience},
year = {2002},
volume = {28},
pages = {1131-1144},
url = {http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6V7D-46TB0P2-3-15&_cdi=5840&_orig=search&_coverDate=12%2F31%2F2002&_sk=999719989&view=c&wchp=dGLbVlb-zSkzV&_acct=C000049009&_version=1&_userid=946230&md5=cc547532c4801b0a61425958b01a8341&ie=f.pdf}
}
|
||||||
| Takeda, A., Cox, S. & Payne, A. J. | 2002 | Parallel numerical modelling of the Antarctic ice sheet. [BibTeX] |
Computers & Geoscience 28 , 723-734 | ISM | antarctica; parallel computing; non-linear partial differential equations; commodity supercomputing; BEDMAP data | |
BibTeX:
@article{takeda2002cg,
author = {Takeda, Andrea and Cox, Simon and Payne, Antony J.},
title = {Parallel numerical modelling of the Antarctic ice sheet.},
journal = {Computers \& Geoscience},
year = {2002},
volume = {28},
pages = {723-734}
}
|
||||||
| Tarasov, L. & Peltier, W. R. | 2004 | A geophysically constrained large ensemble analysis of the deglacial history of the North American ice-sheet complex | Elsevier Quaternary Science Reviews 23 (3-4) , 359-388 | ISM, uncertainty | DOI |
|
| Abstract: Past reconstructions of the deglaciation history of the North American (NA) ice-sheet complex have relied either on largely unconstrained and limited explorations of the phase space of solutions produced by glaciological models or upon geophysical inversions of relative sea-level (RSL) data which suffer from incomplete geographic coverage of the glaciated regions, load history amplitude/timing ambiguities, and a lack of a priori glaciological self-consistency. As a first step in the development of a much more highly constrained deglaciation history, we present a synthesis of these two previously disjoint methodologies based on a large ensemble of glacial cycle simulations using a three-dimensional thermo-mechanically coupled ice-sheet model. Twenty glacial system model parameters, chosen so as to best cover the true deglacial phase space, were varied across the ensemble. Furthermore, a new high-resolution digitized ice margin chronology was imposed on the model in order to significantly limit the uncertainties associated with deglacial climate forcing. The model is simultaneously constrained by a large set of high-quality RSL histories, a space geodetic observation of the present-day rate of vertical motion of the crust from Yellowknife and a traverse of absolute gravity measurements from the west coast of Hudson Bay southward into Iowa. The general form of the Last Glacial Maximum (LGM) ice topography that ensues when model results are subject to geophysical constraints is an ice sheet dominated by a large (3.3–4.3 km maximum ice thickness) Keewatin dome to the west of Hudson Bay connected to a major ice ridge running southeast to the Great Lakes, together with a Hudson Bay region that has relatively thin ice and an Arctic region heavily incised by open water and/or ice shelves. Geographically restricted fast flows due to sub-glacial till deformation are shown to be critical to obtaining such a multi-domed late glacial Laurentide Ice Sheet structure, one that has been previously inferred on the basis of geomorphological data and that is required to fit the geophysical constraints. Our results further suggest that the NA contribution to LGM eustatic sea-level drop is likely to be in the range of 60–75 m. |
||||||
BibTeX:
@article{Tarasov2004QSR,
author = {Tarasov, L. and Peltier, W. Richard},
title = {{A geophysically constrained large ensemble analysis of the deglacial history of the North American ice-sheet complex}},
journal = {Quaternary Science Reviews},
publisher = {Elsevier},
year = {2004},
volume = {23},
number = {3-4},
pages = {359-388},
doi = {10.1016/j.quascirev.2003.08.004}
}
|
||||||
| Tarboton, D. G. | 1999 | TARDEM, a Suite of Programs for the Analysis of Digital Elevation Data. [BibTeX] |
Utah State University | DEM | URL |
|
BibTeX:
@manual{Tarboton1999,
author = {Tarboton, David G.},
title = {{TARDEM, a Suite of Programs for the Analysis of Digital Elevation Data.}},
year = {1999},
url = {http://www.engineering.usu.edu/cee/faculty/dtarb/tardem.html}
}
|
||||||
| Tarboton, D. G. | 1997 | A new method for the determination of flow directions and upslope areas in grid digital elevation models. | Water Resources Research 33 (2) , 309-319 | DEM | hydrology; geomorphology; | URL |
| Abstract: A new procedure for the representation of flow directions and calculation of upslope areas using rectangular grid digital elevation models is presented. The procedure is based on representing flow direction as a single angle taken as the steepest downwards slope on the eight triangular facets centered at each grid point. Upslope area is then calculated by proportioning flow between two downslope pixels according to how close this flow direction is to the direct angle to the downslope pixel. This procedure offers improvements over prior procedures that have restricted flow to eight possible directions (introducing grid bias) or proportioned flow according to slope (introducing unrealistic dispersion). The new procedure is more robust than prior procedures based on fitting local planes while retaining a simple grid based structure. Detailed algorithms are presented and results are demonstrated through test examples and application to digital elevation data sets. | ||||||
BibTeX:
@article{Tarboton1997WRR,
author = {Tarboton, David G.},
title = {A new method for the determination of flow directions and upslope areas in grid digital elevation models.},
journal = {Water Resources Research},
year = {1997},
volume = {33},
number = {2},
pages = {309-319},
url = {http://scholar.google.com/url?sa=U&q=http://www.engineering.usu.edu/dtarb/dinf.pdf}
}
|
||||||
| Tatang, M. A., Pan, W. & Prinn, Ronald G. McRael, G. J. | 1997 | An efficient method for parametric uncertainty analysis of numerical geophysical models. | Journal of Geophysical Research 102 (D18) , 21925-21932 | uncertainty | URL |
|
| Abstract: A new method for parametric uncertainty analysis of numerical geophysical models is presented. It approximates model response surfaces, which are functions of model input parameters, using orthogonal polynomials, whose weighting functions are the probabilistic density functions (PDFs) of the input uncertain parameters. This approach has been applied to the uncertainty analysis of an analytical model of the direct radiative forcing by anthropogenic sulfate aerosols which has nine uncertain parameters. This method is shown to generate PDFs of the radiative forcing which are very similar to the exact analytical PDF. Compared with the Monte Carlo method for this problem, the new method is a factor of 25 to 60 times faster, depending on the error tolerance, and exhibits an exponential decrease of error with increasing order of the approximation. | ||||||
BibTeX:
@article{Tatang1997JGR,
author = {Tatang, Menner A. and Pan, Wenwei and Prinn, Ronald G. McRael, Gregory J.},
title = {An efficient method for parametric uncertainty analysis of numerical geophysical models.},
journal = {Journal of Geophysical Research},
year = {1997},
volume = {102},
number = {D18},
pages = {21925-21932},
url = {http://www.agu.org/pubs/crossref/1997/97JD01654.shtml}
}
|
||||||
| Thompson, S. L. & Pollard, D. | 1997 | Greenland and Antarctic Mass Balances for Present and Doubled Atmospheric CO$_2$ from the GENESIS Version-2 Global Climate Model. | Journal of Climate 10 (5) , 871-900 | ISM | DOI |
|
| Abstract: As anthropogenic greenhouse warming occurs in the next century, changes in the mass balances of Greenland and Antarctica will probably accelerate and may have significant effects on global sea level. Recent trends and possible future changes in these mass balances have received considerable attention in the glaciological literature, but until recently relatively few general circulation modeling (GCM) studies have focused on the problem. However, there are two significant problems in using GCMs to predict mass balance distributions on ice sheets: (i) the relatively coarse GCM horizontal resolution truncates the topography of the ice-sheet flanks and smaller ice sheets such as Greenland, and (ii) the snow and ice physics in most GCMs does not include ice-sheet-specific processes such as the refreezing of meltwater. Two techniques are described that attack these problems, involving (i) an elevation-based correction to the surface meteorology and (ii) a simple a posteriori correction for the refreezing of meltwater following Pfeffer et al Using these techniques in a new version 2 of the Global Environmental and Ecological Simulation of Interactive Systems global climate model, the authors present global climate and ice-sheet mass-balance results from two equilibrated runs for present and doubled atmospheric CO2. This GCM is well suited for ice-sheet mass-balance studies because (a) the surface can be represented at a finer resolution (2° lat × 2° long) than the atmospheric GCM, (b) the two correction techniques are included as part of the model, and (c) the model’s mass balances for present-day Greenland and Antarctica are realistic. When atmospheric CO2 is doubled, the net annual surface mass balance decreases on Greenland from +13 to −12 cm yr−1 and increases on Antarctica from +18 to +21 cm yr−1. The corresponding changes in the ice-sheet contributions to global sea level are +1.2 and −1.3 mm yr−1, respectively, yielding a combined contribution of −0.1 mm yr−1. That would be a very minor component of the total sea level rise of ∼5 mm yr−1 expected in the next century, mainly from thermal expansion of the oceans and melting of smaller glaciers. However, biases in the GCM climate suggest a range of uncertainty in the ice-sheet contribution from about −2 to +1 mm yr−1. |
||||||
BibTeX:
@article{Thompson1997JC,
author = {Thompson, Starley L. and Pollard, David},
title = {{Greenland} and {Antarctic} Mass Balances for Present and Doubled Atmospheric {CO$_2$} from the {GENESIS} Version-2 Global Climate Model.},
journal = {Journal of Climate},
year = {1997},
volume = {10},
number = {5},
pages = {871-900},
doi = {10.1175/1520-0442(1997)010<0871:GAAMBF>2.0.CO;2}
}
|
||||||
| Tobler, W. R. | 1970 | A computer movie simulating urban growth in the Detroit region. [BibTeX] |
Economic Geography 46 , 230-240 | GIS | ||
BibTeX:
@article{Tobler1970EG,
author = {Tobler, Waldo R.},
title = {A computer movie simulating urban growth in the {Detroit} region.},
journal = {Economic Geography},
year = {1970},
volume = {46},
pages = {230-240}
}
|
||||||
| Tucker, G. E., Lancaster, S. T., Gasparini, N. M., Bras, R. L. & Rybarczyk, S. M. | 2001 | An object-oriented framework for hydrologic and geomorphic modeling using Triangulated Irregular Networks. | Computers & Geoscience 27 (8) , 959-973 | DEM | URL |
|
| Abstract: We describe a newset of data structures and algorithms for dynamic terrain modeling using a triangulated irregular network (TINs). The framework provides an efficient method for storing, accessing, and updating a Delaunay triangulation and its associated Voronoi diagram. The basic data structure consists of three interconnected data objects: triangles, nodes, and directed edges. Encapsulating each of these geometric elements within a data object makes it possible to essentially decouple the TIN representation from the modeling applications that make use of it. Both the triangulation and its corresponding Voronoi diagram can be rapidly retrieved or updated, making these methods well suited to adaptive remeshing schemes. We develop a set of algorithms for defining drainage networks and identifying closed depressions (e.g., lakes) for hydrologic and geomorphic modeling applications. We also outline simple numerical algorithms for solving network routing and 2D transport equations within the TIN framework. The methods are illustrated with two example applications, a landscape evolution model and a distributed rainfall-runoff model. |
||||||
BibTeX:
@article{tucker2001cg,
author = {Tucker, G. E. and Lancaster, S. T. and Gasparini, N. M. and Bras, R. L. and Rybarczyk, S. M.},
title = {An object-oriented framework for hydrologic and geomorphic modeling using Triangulated Irregular Networks.},
journal = {Computers \& Geoscience},
year = {2001},
volume = {27},
number = {8},
pages = {959-973},
url = {http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6V7D-43CHB1B-7-30&_cdi=5840&_user=946230&_orig=browse&_coverDate=10%2F31%2F2001&_sk=999729991&view=c&wchp=dGLbVzz-zSkWW&md5=7c62bd87aefba818d60a18c223972935&ie=/sdarticle.pdf}
}
|
||||||
| Tucker, G. E. & Whipple, K. X. | 2002 | Topographic outcomes predicted by stream erosion models: Sensitivity analysis and intermodel comparison. | Journal of Geophysical Research 107 (B9) , 2179 | DEM | landscape evolution; topography; erosion; streams; relief; hydrology | DOI URL |
| Abstract: Mechanistic theories of fluvial erosion are essential for quantifying large-scale orogenic denudation. We examine the topographic implications of two leading classes of river erosion model, detachment-limited and transport-limited, in order to identify diagnostic and testable differences between them. Several formulations predict distinctly different longitudinal profile shapes, which are shown to be closely linked to terrain morphology. Of these, some can be rejected on the basis of unrealistic morphology and slope-area scaling. An expression is derived for total drainage basin relief and its apportionment between hillslope and fluvial components. Relief and valley density are found to vary with tectonic forcing in a manner that reflects erosion physics; these properties therefore constitute an additional set of testable predictions. Finally, transient responses to tectonic perturbations are shown to depend strongly on the degree of nonlinearity in the incision process. These findings indicate that given proper constraints, fluvial erosion theories can be tested on the basis of observed topography. |
||||||
BibTeX:
@article{tucker2002top,
author = {Tucker, G. E. and Whipple, K. X.},
title = {Topographic outcomes predicted by stream erosion models: Sensitivity analysis and intermodel comparison.},
journal = {Journal of Geophysical Research},
year = {2002},
volume = {107},
number = {B9},
pages = {2179},
url = {http://www.colorado.edu/geolsci/gtucker/preprints/2001JB000162.pdf},
doi = {10.1029/2001JB000162}
}
|
||||||
| Survey, U. G. | 1996 | GTOPO30: Global 30 Arc Second Elevation Data. | DEM | |||
| Abstract: GTOPO30 is a global digital elevation model (DEM) with a horizontal grid spacing of 30 arc seconds (approximately 1 kilometer). GTOPO30 was derived from several raster and vector sources of topographic information. For easier distribution, GTOPO30 has been divided into tiles which can be selected from the map shown above. Detailed information on the characteristics of GTOPO30 including the data distribution format, the data sources, production methods, accuracy, and hints for users, is found in the GTOPO30 README file. GTOPO30, completed in late 1996, was developed over a three year period through a collaborative effort led by staff at the U.S. Geological Survey's Center for Earth Resources Observation and Science (EROS). The following organizations participated by contributing funding or source data: the National Aeronautics and Space Administration (NASA), the United Nations Environment Programme/Global Resource Information Database (UNEP/GRID), the U.S. Agency for International Development (USAID), the Instituto Nacional de Estadistica Geografica e Informatica (INEGI) of Mexico, the Geographical Survey Institute (GSI) of Japan, Manaaki Whenua Landcare Research of New Zealand, and the Scientific Committee on Antarctic Research (SCAR). |
||||||
BibTeX:
@misc{USGS1996gtopo30,
author = {{U.S. Geological Survey}},
title = {{GTOPO30}: Global 30 Arc Second Elevation Data.},
year = {1996},
note = {EROS Data Center Distributed Active Archive Center (EDC DAAC), Sioux Falls, SD.}
}
|
||||||
| Vaughan, D. G. & Spouge, J. R. | 2002 | Risk Estimation of Collapse of the West Antarctic Ice Sheet | Springer Climate Change 52 (1) , 65-91 | ISM | DOI |
|
| Abstract: Complete collapse of the West Antarctic Ice Sheet (WAIS) would raise global sea level by around 5 m, but whether collapse is likely, or even possible, has been `glaciology's grand unsolved problem' for more than two decades. Collapse of WAIS may result from readjustments continuing since the last glacial maximum, or more recent climate change, but it is also possible that collapse will result from internal flow instabilities, or not occur at all in the present inter-glacial. Such complexity led the Intergovernmental Panel on Climate Change to conclude in its Second Assessment Report that `estimating the likelihood of a collapse during the next century is not yet possible'. However, a refusal by scientists to estimate the risk leaves policy-makers with no sound scientific basis on which to respond to legitimate public concerns. Here we present a discussion of the likelihood of WAIS-collapse, drawing input from an interdisciplinary panel of experts. The results help to summarise the state of scientific knowledge and uncertainty. While the overall opinion of the panel was that WAIS most likely will not collapse in the next few centuries, their uncertainty retains a 5% probability of WAIS causing sea level rise at least 10 mm/year within 200 years. Since this uncertainty reflects both the unpredictability of the physical system and the scientific uncertainty, it will undoubtedly change as a better understanding is established. | ||||||
BibTeX:
@article{Vaughan2002CC,
author = {Vaughan, David G. and Spouge, John R.},
title = {{Risk Estimation of Collapse of the West Antarctic Ice Sheet}},
journal = {Climate Change},
publisher = {Springer},
year = {2002},
volume = {52},
number = {1},
pages = {65-91},
doi = {10.1023/A:1013038920600}
}
|
||||||
| van der Veen, C. | 2002 | Polar ice sheets and global sea level: how well can we predict the future? | Global and Planetary Change 32 , 165-194 | uncertainty; ISM | Polar ice sheets; Global sea level; Mass balance models | DOI |
| Abstract: Geophysical models are based on hypotheses that are often derived from theoretical arguments or from observations, or a combination of both. Owing to the open nature of geophysical systems, these models cannot be verified in the sense that it cannot be proven that the model is an accurate representation of the physical reality. At best these models can be confirmed by comparing model predictions against independent observations. The more such observations the model agrees with, the greater confidence can be placed in the model and its reliability as a basis for decision making. A review of mass balance models used to predict past and future contributions to global sea level change arising from changes in snow accumulation and surface ablation on the polar ice sheets is presented. Observations on which these models are based are ambiguous and there is evidence suggesting that these models do not capture all relevant physical processes, some of which - such as changes in atmospheric circulation patterns - may have an equally important effect on changes in surface mass balance as does the direct temperature forcing. In the context of greenhouse-warming-induced sea level change, uncertainties in model parameters are sufficiently great to yield a range of projected contributions from Greenland and Antarctica that encompass sea-level lowering and rise in 2100 A.D. for each of the warming scenarios considered. The uncertainty associated with ice sheet mass balance parameterizations is of similar magnitude as that associated with temperature projections. These results are broadly similar to those of the Third Assessment Report issued by the Intergovernmental Panel on Climate Change (IPCC). | ||||||
BibTeX:
@article{Veen2002GPC,
author = {van der Veen, C.J.},
title = {Polar ice sheets and global sea level: how well can we predict the future?},
journal = {Global and Planetary Change},
year = {2002},
volume = {32},
pages = {165-194},
doi = {10.1016/S0921-8181(01)00140-0}
}
|
||||||
| Verdin, K. L. & Jenson, S. K. | 1996 | Development of Continental Scale DEMs and Extraction of Hydrographic Features. | EROS Data Center | DEM | hydrology; DEM; | URL |
| Abstract: Continental scale digital elevation models (DEMs) are required for climate and global change studies spanning a variety of disciplines: atmospheric science, hydrology, biogeochemistry, wildlife biology, forestry, range science, and others. To date the only available data set with global coverage has been ETOPO5 (National Geophysical Data Center, 1988) which, with its 5 arc- minute (approximately 10 kilometer resolution, has proven inadequate for many applications. To better address the requirements of the scientific community, the U.S. Geological Survey (USGS) has undertaken to provide DEM data sets for all the earth's land masses at 30 arc-second (approximately 1 km) resolution. USGS scientists are working with the Defense Mapping Agency (DMA) to develop procedures for generalizing 3 arc-second (approximately 90 meter) digital terrain elevation data (DTED 1) for large land masses. For areas where DTED 1 is not available, DMA's Digital Chart of the World (DCW) is being used as a source to generate elevation data, using a gridding algorithm that captures contours, spot heights, and hydrology with drainage enforcement. Techniques were developed to blend the DCW-derived DEM data with the generalized DTED. To date (January 1996), Africa, North America, Europe and Asia are complete and are being made available, free of charge, to the public via internet transfer. A 30 arc-second DEM of Antarctica is being finalized with distribution anticipated for early 1996. Work is progressing on the continents of South America and Australia, with an anticipated completion date of October 1996. In addition to providing the raw elevation data, the DEMs are being processed to extract hydrographic features. The North American DEM was used as a prototype to demonstrate the feasibility of extracting basins and flowlines from the USGS 30 arc-second DEMs. Derived basins and flowlines were verified with independently mapped source material. | ||||||
BibTeX:
@techreport{verdin1996gtopo,
author = {Verdin, Kristine L. and Jenson, Susan K.},
title = {Development of Continental Scale DEMs and Extraction of Hydrographic Features.},
year = {1996},
url = {http://edcdaac.usgs.gov/gtopo30/papers/santafe3.asp}
}
|
||||||
| Veregin, H. | 1989 | Accuracy of Spatial Databases. [BibTeX] |
Taylor & Francis, London , 3-18 | GIS | ||
BibTeX:
@inbook{Veregin1989inbook,
author = {Veregin, H.},
title = {Accuracy of Spatial Databases.},
publisher = {Taylor \& Francis, London},
year = {1989},
pages = {3-18}
}
|
||||||
| van de Wal, R. | 1999 | The importance of thermodynamics for modeling the volume of the Greenland ice sheet. | Journal of Geophysical Research 104 (D4) , 3887-3898 | ISM | ||
| Abstract: Two different kinds of ice flow models, one two-dimensional (2-D) and the other three-dimensional (3-D), have been used to test the importance of the thermodynamic response of the Greenland ice sheet. The basic difference between the two models is that the thermodynamics are neglected in the two-dimensional model, whereas these are incorporated in the three-dimensional model. The 2-D and 3-D models are compared in terms of volume response time and total volume of the ice sheet. Results indicate that the sawtooth character of the ice volume on glacial-interglacial timescales is, among other possible reasons, a result of the thermodynamic coupling. The changes in elevation over the last 130,000 years calculated with the three-dimensional version are 230 m for the Summit drill site and 190 m for the N-GRIP site. The standard deviation of the changes in elevation is 55 m for the Summit site and 43 m for the N-GRIP site. The present-day imbalance is merely a result of the rather constant climate over the last 10 kyr and is not determined by the thermodynamics. Consequently, Pleistocene temperatures do still exist in the ice sheet but are not important for volume calculations of the present-day ice sheet. For short-term perturbation experiments in the future, the pronounced sensitivity of the mass balance will determine the response of the Greenland ice sheet, whereas thermodynamics will play only a minor role. | ||||||
BibTeX:
@article{Wal1999JGR,
author = {van de Wal, R.S.W.},
title = {The importance of thermodynamics for modeling the volume of the {Greenland} ice sheet.},
journal = {Journal of Geophysical Research},
year = {1999},
volume = {104},
number = {D4},
pages = {3887-3898}
}
|
||||||
| van de Wal, R. & Ekholm, S. | 1996 | On elevation models as input for mass-balance calculations of the Greenland ice sheet. [BibTeX] |
Annals of Glaciology 23 , 181-186 | ISM | mass balance; elevation model; Greenland; ice sheet | |
BibTeX:
@article{vandewal1996agla,
author = {van de Wal, R.S.W. and Ekholm, S.},
title = {On elevation models as input for mass-balance calculations of the {Greenland} ice sheet.},
journal = {Annals of Glaciology},
year = {1996},
volume = {23},
pages = {181-186}
}
|
||||||
| van de Wal, R. S. W. & Oerlemans, J. | 1994 | An Energy-Balance Model for the Greenland Ice-Sheet. | Global and Planetary Change 9 , 115-131 | ISM | ||
| Abstract: The sensitivity of the mass balance of the Greenland Ice Sheet is studied by means of an energy balance model. The model calculates the shortwave and longwave radiation and the turbulent fluxes on a grid with a grid point spacing of 20 km. Special attention is given to the parameterization of the albedo. The albedo is calculated as a function of snow depth, ablation, amount of meltwater at the surface and the type of surface. The response of the model to changing climatic input is nonlinear. As a result the ablation drifts to higher values when temporal variability of input is imposed. Climate change experiments reveal a large sensitivity of the mean ablation to small changes in the temperature. A 1K rise in temperature leads to approximately 30% more ablation. Further experiments with this model suggest that the contribution of the Greenland ice sheet to past global sea level rise has been 35 +/- 18 mm over the last 120 years. Applying the Bellaggio scenario as a forcing function results in a doubling of the ablation by 2100 AD. The corresponding contribution to global sea level rise is 6 cm over the period 1985-2100 AD. | ||||||
BibTeX:
@article{vandeWal1994GPC,
author = {van de Wal, R. S. W. and Oerlemans, J.},
title = {An Energy-Balance Model for the {Greenland} Ice-Sheet.},
journal = {Global and Planetary Change},
year = {1994},
volume = {9},
pages = {115-131}
}
|
||||||
| Walker, J. P. & Willgoose, G. R. | 1999 | On the effect of digital elevation model accuracy on hydrology and geomorphology. | Water Resources Research 35 (7) , 2259-2268 | DEM | DEM; hydrology; error; accuracy; | DOI URL |
| Abstract: This study compares published cartometric and photogrammetric digital elevation models (DEMs) of various grid spacings with a ground truth data set, obtained by ground survey, and studies the implications of these differences on key hydrologic statistics. Inferred catchment sizes and stream networks from published DEMs were found to be significantly different than those from the ground truth in most instances. Furthermore, the width functions and cumulative area relationships determined from the published DEMs were found to fall consistently outside the 90% confidence limits determined from the ground truth for more than 60% of the relationship, suggesting that these hydrologic properties are poorly estimated from published DEMs. However, the slope-area relationships determined from published DEMs were found to be less sensitive to catchment shape, size, and stream network, with the relationship falling outside the 90% confidence limits for less than 40% of the relationship for all catchments identified from the published DEMs. A published relationship linking the horizontal resolution with the vertical accuracy of the DEM was tested, predicting a horizontal resolution of about 10 m for the published DEMs tested. |
||||||
BibTeX:
@article{Walker1999WRR,
author = {Walker, Jeffrey P. and Willgoose, Garry R.},
title = {On the effect of digital elevation model accuracy on hydrology and geomorphology.},
journal = {Water Resources Research},
year = {1999},
volume = {35},
number = {7},
pages = {2259-2268},
url = {http://www.civenv.unimelb.edu.au/~jwalker/papers/wrr99.pdf},
doi = {0043-1397/99/1999WR900034$09.00}
}
|
||||||
| Walker, P. A. & Grant, I. | 1986 | Quadtree: A FORTRAN program to extract the quadtree structure of a raster format multicolored image. [BibTeX] |
Computers & Geoscience 12 , 401-410 | URL |
||
BibTeX:
@article{Walker1986CG,
author = {Walker, P. A. and Grant, I.W.},
title = {Quadtree: A FORTRAN program to extract the quadtree structure of a raster format multicolored image.},
journal = {Computers \& Geoscience},
year = {1986},
volume = {12},
pages = {401-410},
url = {http://portal.acm.org/citation.cfm?id=16495&jmp=cit&dl=GUIDE&dl=GUIDE,ACM&CFID=24056543&CFTOKEN=46346182#CIT}
}
|
||||||
| Wang, X. & Dang, A. | 2000 | Membership grade normalization of GIS uncertainty model and two fuzzy overlay algorithms. | Geoscience and Remote Sensing Symposium, 2000. Proceedings. IGARSS 2000. IEEE 2000 International , 2131-2133 | uncertainty | DOI |
|
| Abstract: Uncertainty research is an important research focus of GIS. Fuzzy set theories provide a good method for GIS uncertainty model to describe the world more externally. Based on fuzzy set theories, membership grade normalization (MGN) applied to GIS temporal dimension, spatial dimension and thematic dimension is proposed. The intersection operator and union operator of traditional fuzzy set theories could not meet MGN. It is necessary to construct a new fuzzy overlay operator. At last, two fuzzy overlay algorithms meeting MGN are given. | ||||||
BibTeX:
@inproceedings{Wang2000,
author = {Wang, Xiaodong and Dang, Anrong},
title = {Membership grade normalization of GIS uncertainty model and two fuzzy overlay algorithms.},
booktitle = {Geoscience and Remote Sensing Symposium, 2000. Proceedings. IGARSS 2000. IEEE 2000 International},
year = {2000},
volume = {5},
pages = {2131-2133},
doi = {10.1109/IGARSS.2000.858330}
}
|
||||||
| Webster, R. & Oliver, M. | 2001 | Geostatistics for environmental scientists. [BibTeX] |
Wiley, Chichester | GIS | ||
BibTeX:
@book{webster2001book,
author = {Webster, R. and Oliver, M.A. },
title = {Geostatistics for environmental scientists.},
publisher = {Wiley, Chichester},
year = {2001}
}
|
||||||
| Wechsler, S. P. | 2007 | Uncertainties associated with digital elevation models for hydrologic applications: a review. | Hydrology and Earth System Sciences 11 (4) , 1481-1500 | DEM, uncertainty | URL |
|
| Abstract: Digital elevation models (DEMs) represent the topography that drives surface flow and are arguably one of the more important data sources for deriving variables used by numerous hydrologic models. A considerable amount of research has been conducted to address uncertainty associated with error in digital elevation models (DEMs) and the propagation of error to derived terrain parameters. This review brings together a discussion of research in fundamental topical areas related to DEM uncertainty that affect the use of DEMs for hydrologic applications. These areas include: (a) DEM error; (b) topographic parameters frequently derived from DEMs and the associated algorithms used to derive these parameters; (c) the influence of DEM scale as imposed by grid cell resolution; (d) DEM interpolation; and (e) terrain surface modification used to generate hydrologically-viable DEM surfaces. Each of these topical areas contributes to DEM uncertainty and may potentially influence results of distributed parameter hydrologic models that rely on DEMs for the derivation of input parameters. The current state of research on methods developed to quantify DEM uncertainty is reviewed. Based on this review, implications of DEM uncertainty and suggestions for the GIS research and user communities are offered. | ||||||
BibTeX:
@article{Wechsler2007HESS,
author = {Wechsler, Suzanne P.},
title = {Uncertainties associated with digital elevation models for hydrologic applications: a review.},
journal = {Hydrology and Earth System Sciences},
year = {2007},
volume = {11},
number = {4},
pages = {1481-1500},
url = {www.hydrol-earth-syst-sci.net/11/1481/2007/}
}
|
||||||
| Wechsler, S. P. | 2006 | Uncertainties associated with digital elevation models for hydrologic applications: a review. | Hydrology and Earth System Sciences Discussions 3 , 2343-2384 | uncertainty | DEM; hydrology; GIS; | URL |
| Abstract: Digital elevation models (DEMs) represent the topography that drives surface flow and are arguably one of the more important data sources for deriving variables used by numerous hydrologic models. A considerable amount of research has been conducted 5 to address uncertainty associated with error in digital elevation models (DEMs) and the propagation of error to derived terrain parameters. This review brings together a discussion of research in fundamental topical areas related to DEM uncertainty that affect the use of DEMs for hydrologic applications. These areas include: (a) DEM error; (b) topographic parameters frequently derived from DEMs and the associated algorithms 10 used to derive these parameters; (c) the influence of DEM scale as imposed by grid cell resolution; (d) DEM interpolation; and (e) terrain surface modification used to generate hydrologically-viable DEM surfaces. Each of these topical areas contributes to DEM uncertainty and may potentially influence results of distributed parameter hydrologic models that rely on DEMs for the derivation of input parameters. The current state of 15 research on methods developed to quantify DEM uncertainty is reviewed. Based on this review, implications of DEM uncertainty and suggestions for the GIS research and user communities emerge. |
||||||
BibTeX:
@article{Wechsler2006HESSD,
author = {Wechsler, Suzanne P.},
title = {Uncertainties associated with digital elevation models for hydrologic applications: a review.},
journal = {Hydrology and Earth System Sciences Discussions},
year = {2006},
volume = {3},
pages = {2343-2384},
url = {http://www.copernicus.org/EGU/hess/hessd/3/2343/hessd-3-2343_p.pdf}
}
|
||||||
| Wechsler, S. P. | 2003 | Perceptions of digital elevation model uncertainty by DEM users. | URISA Journal 15 (2) , 57-64 | DEM | DEM; uncertainty; user perception | URL |
| Abstract: A survey of digital elevation model (DEM) users was conducted to investigate how respondents use elevation data and how they perceive and address DEM uncertainty arising from unknown error in the elevation data. The information reported here is based on 216 survey responses received between June 4, 1998 and June 4, 2000. DEM users from 26 countries and various organizations and industries participated in the survey. Half of the respondents recognized that their work is “sometimes� or “always� affected by uncertainty, and 55% indicated that uncertainty is “very important� or “somewhat important.� Respondents reported that they would spend a minimum amount of time to assess DEM uncertainty. The methods used by the small group of respondents who “always� account for uncertainty (21%) were varied. There does not appear to be consistent procedures for addressing uncertainty among the community of DEM users. The effects of DEM uncertainty should be explicit, and procedures for addressing it should be consistent so that conclusions from DEM-based analyses take uncertainty into account. |
||||||
BibTeX:
@article{Wechsler2003URISA,
author = {Wechsler, Suzanne P.},
title = {Perceptions of digital elevation model uncertainty by {DEM} users.},
journal = {URISA Journal},
year = {2003},
volume = {15},
number = {2},
pages = {57-64},
url = {http://urisa.org/Journal/protect/Vol15No2/Wechsler.pdf}
}
|
||||||
| Wechsler, S. P. | 2000 | Effect of DEM uncertainty on topographic parameters, DEM scale and terrain evaluation. | Dissertation State University of New York, College of Environmental Science and Forestry, Syracuse, New York | DEM | Digital Elevation Model, DEM, Geographic Information System, GIS, uncertainty, simulation, Monte Carlo, ESRI, ArcView Spatial Analyst, slope, upslope area, topographic index | URL |
| Abstract: Digital Elevation Models (DEMs) are representations of topography with inherent errors that constitute uncertainty. DEM data are often used in analyses without quantifying the effects of these errors. DEMs are a commonly utilized standard data source for GIS based studies aimed at evaluating natural processes. This research developed a methodology to quantify uncertainty in the DEM and derived parameters of slope, upslope contributing area, and the topographic index (TI). The methodology was implemented within the ESRI ArcView Spatial Analyst? GIS environment and utilizes Monte Carlo simulations to quantify DEM uncertainty using random error fields. Different methods for simulating random error were developed. The methodology and resulting tool were applied to investigate: (a) effects of uncertainty on elevation and derived topographic parameters, (b) effects of uncertainty on DEMs of different scale (30m and 10m resolution), and (c) effects of uncertainty in flat and varied terrain. Parameter estimator statistics enabled quantification of DEM error. Results demonstrate the applicability of the methodology in quantifying and depicting the impacts of DEM random error. DEM parameters were affected by random error; this effect varied with the method in which random error was represented. DEM error manifested itself differently in DEMs of different scales. At higher grid resolution, slope and TI were more susceptible to DEM error than elevation and upslope area. In the study that compared uncertainty in flat and varied terrain, slope and upslope area grids were more sensitive to uncertainty than elevation and topographic index grids with a more pronounced effect in flatter areas. Each study demonstrated a bias contributed by sink filling in lower valley areas that could have implications for research that relies on DEMs for parameters in these areas such as agricultural watersheds. | ||||||
BibTeX:
@phdthesis{Wechsler2000diss,
author = {Wechsler, Suzanne P.},
title = {Effect of {DEM} uncertainty on topographic parameters, {DEM} scale and terrain evaluation.},
school = {State University of New York, College of Environmental Science and Forestry, Syracuse, New York},
year = {2000},
url = {http://www.csulb.edu/~wechsler/Dissertation/DissPage.html}
}
|
||||||
| Wechsler, S. P. | 1999 | Digital Elevation Model (DEM) Uncertainty: Evaluation and Effect on Topographic Parameters. | ESRI User Conference 1999 Proceedings. | DEM | DEM; uncertainty; | |
| Abstract: Digital Elevation Models (DEMs) are representations of topography with inherent errors that constitute uncertainty. DEM data are often used in analyses without quantifying the effects of these errors. A method for simulating uncertainty that is implemented as an extension for the ArcView/Spatial Analyst GIS environment was developed. Users can evaluate DEM uncertainty using DEM metadata and spatial characteristics of the DEM. Monte-Carlo simulation techniques were used to represent DEM uncertainty and its effect on various topographic parameters (slope, upslope area, and the topographic index) often used in hydrologic analyses. Different methods for representing error and quantifying uncertainty were investigated. | ||||||
BibTeX:
@inproceedings{Wechsler1999esri,
author = {Wechsler, Suzanne P.},
title = {Digital Elevation Model ({DEM}) Uncertainty: Evaluation and Effect on Topographic Parameters.},
booktitle = {ESRI User Conference 1999 Proceedings.},
year = {1999}
}
|
||||||
| Wechsler, S. P. & Kroll, C. N. | 2006 | Quantifying DEM Uncertainty and its effects on topographic parameters. | Photogrammetric Engineering and Remote Sensing 72 (9) , 1081-1090 | Uncertainty | ||
| Abstract: Digital elevation models (DEMs) are representations of topography with inherent errors that constitute uncertainty. DEM data are often used in analyses without quantifying the effects of these errors. This paper describes a Monte Carlo methodology for evaluation of the effects of uncertainty on elevation and derived topographic parameters. Four methods for representing DEM uncertainty that utilize meta-data and spatial characteristics of a DEM are presented. Seven statistics derived from simulation results were used to quantify the effect of DEM error. When uncertainty was quantified by the average relative absolute difference, elevation did not deviate. The range of deviation across the four methods for slope was 5 to 8 percent, 460 to 950 percent for derived catchment areas and 4 to 9 percent for the topographic index. This research demonstrates how application of this methodology can address DEM uncertainty, contributing to more responsible use of elevation and derived topographic parameters, and ultimately results obtained from their use. | ||||||
BibTeX:
@article{Wechsler2006PERS,
author = {Wechsler, Suzanne P. and Kroll, Charles N.},
title = {Quantifying {DEM} Uncertainty and its effects on topographic parameters.},
journal = {Photogrammetric Engineering and Remote Sensing},
year = {2006},
volume = {72},
number = {9},
pages = {1081-1090}
}
|
||||||
| Weibel, R. & Buttenfield, B. P. | 1992 | Improvement of GIS graphics for analysis and decision-making . | International Journal of Geographical Information Science 6 (3) , 223-245 | GIS, uncertainty | DOI |
|
| Abstract: Current geographical information systems (GIS) include functions to create cartographic output interactively or automatically. However, none of the systems presently incorporates mechanisms to ensure correct application of graphic functions. Many of today's users of GIS are not trained in the design and production of graphics and may create maps that confuse or mislead map users. Poorly-designed maps may obliterate the patterns in displayed information. This article investigates ways to improve the quality of GIS graphical displays and increase their effectiveness for decision-making. Alternatives are presented for improving map design in GIS, ranging from non-technical efforts to enhancement of software functionality. Suggestions propose augmenting users' abilities to create maps in an automated environment, using an approach termed amplified intelligence: key decisions default explicitly to users, whose knowledge is amplified by a range of high-level tools to carry out map design operations automatically. |
||||||
BibTeX:
@article{Weibel1992IJGIS,
author = {Weibel, Robert and Buttenfield, Barabara P.},
title = {Improvement of {GIS} graphics for analysis and decision-making .},
journal = {International Journal of Geographical Information Science},
year = {1992},
volume = {6},
number = {3},
pages = {223-245},
doi = {10.1080/02693799208901907}
}
|
||||||
| Weibel, R. & Heller, M. | 1991 | Digital terrain modelling. | Geographical Information Systems: Principles and Applications. John Wiley & Sons, Inc., Chichester , 269-297 | DEM | DEM; GIS; | URL |
| Abstract: Digital terrain models (DTMs) are a major constituent of geographical information processing. DTMs help to model, analyse and display phenomena related to topography or similar surfaces. This chapter is an attempt at a comprehensive review of relevant techniques and applications of DTMs. The individual elements of digital terrain modelling - techniques for the generation, manipulation, interpretation (analysis) and visualization of DTMs - are outlined. Application domains that use DTMs and their specijic functional requirements are identijied. Due to the complexity of the topic this chapter should be considered primarily as an annotated guide to the rich literature on digital terrain modelling. | ||||||
BibTeX:
@incollection{weibel1991book,
author = {Weibel, Robert and Heller, M.},
title = {Digital terrain modelling.},
booktitle = {Geographical Information Systems: Principles and Applications.},
publisher = {John Wiley \& Sons, Inc., Chichester},
year = {1991},
pages = {269-297},
url = {http://www.wiley.com/legacy/wileychi/gis/Volume1/BB1v1_ch19.pdf}
}
|
||||||
| Weng, Q. | 2002 | Quantifying Uncertainty of Digital Elevation Models Derived from Topographic Maps. | Advances in Spatial Data Handling. Springer, Berlin , 403-418 | DEM, uncertainty | DEM; uncertainty; origins; distributional measures; | URL |
| Abstract: This paper explores a methodology for quantifying the uncertainty of DEMs created by digitising topographic maps. The origins of uncertainty in DEM production were identified and examined. The uncertainty of DEM data was quantified by computing a vector total of Root Mean Square Error (RMSE) from the source map, sampling and measurement errors, and the interpolation process. Distributional measures including accuracy surfaces, spatial autocorrelation indices, and variograms were also employed to quantify the magnitude and spatial pattern of the uncertainty. The test for this methodology utilises a portion of a 1:24 000 topographic map centred on Stone Mountain in northeastern Georgia, USA. Five DEMs, constructed with different interpolation algorithms, are found to have the total RMSE ranging from 4.39 to 9.82 meters, and a highly concentrated pattern of uncertainty in rugged terrain. This study suggests that the RMSE provides only a general indicator of DEM uncertainty. Detailed studies should use distributional measures to understand how the uncertainty varies over a surface. |
||||||
BibTeX:
@incollection{Weng2002inbook,
author = {Weng, Q.},
title = {Quantifying Uncertainty of Digital Elevation Models Derived from Topographic Maps.},
booktitle = {Advances in Spatial Data Handling.},
publisher = {Springer, Berlin},
year = {2002},
pages = {403-418},
url = {http://isu.indstate.edu/qweng/Chapter_30.pdf}
}
|
||||||
| Wenzens, G. | 2003 | Comment on: 'The Last Glacial Maximum and deglaciation in southern South America' by N.R.J. Hulton, R.S. Purves, R.D. McCulloch, D.E. Sugden, M.J. Bentley [Quaternary Science Reviews 21 (2002) 233-241] [BibTeX] |
Quaternary Science Reviews 22 (5-7) , 751-754 | ISM | DOI |
|
BibTeX:
@article{Wenzens2003QSR,
author = {Wenzens, G.},
title = {Comment on:{ 'The Last Glacial Maximum and deglaciation in southern South America' by N.R.J. Hulton, R.S. Purves, R.D. McCulloch, D.E. Sugden, M.J. Bentley [Quaternary Science Reviews 21 (2002) 233-241]}},
journal = {Quaternary Science Reviews},
year = {2003},
volume = {22},
number = {5-7},
pages = {751-754},
doi = {10.1016/S0277-3791(02)00165-8}
}
|
||||||
| WGMS-Team | 1998 | Monitoring strategy of the World Glacier Monitoring Service (WGMS). [BibTeX] |
World Glacier Monitoring Service | ISM | Glacier mass balance, glacier inventories, glacier length chance, data analysis and monitoring strategy | URL |
BibTeX:
@techreport{wgms-team1998report,
author = {WGMS-Team},
title = {Monitoring strategy of the World Glacier Monitoring Service {(WGMS)}.},
year = {1998},
url = {http://www.geo.unizh.ch/wgms/monitoring.html}
}
|
||||||
| Willgoose, G. | 2005 | Mathematical Modeling of Whole Landscape Evolution. | Annual Review of Earth and Planetary Sciences 33 , 443-459 | GIS, DEM | DOI |
|
| Abstract: The mathematical modeling of landform evolution consists of two components: the processes represented (i.e., considered dominant) in the model and the (typically computer) model representation of these processes. This review discusses the current debates surrounding processes represented in landform evolution. The potential impact on both evolving landforms and computer model structure is discussed. Issues specifically discussed include (a) the fundamental nature of mass conservation and the role of detachment- and transport-limited processes in mass conservation equations, (b) the interaction between detachment- and transport-limitation in channels, (c) the role of hillslope erosion and soil properties and their interaction with channel processes, (d) the interactions with tectonics when applying these models at large scale, (e) depositional structures and implications for paleo-climatic interpretation, (f) engineering applications of these models, and (g) numerical issues in the computer implementations. This review is not a model comparison. However, many applications are at the boundaries of computer capabilities so a comparison of existing models is provided. | ||||||
BibTeX:
@article{Willgoose2005AREPS,
author = {Willgoose, Gary},
title = {Mathematical Modeling of Whole Landscape Evolution.},
journal = {Annual Review of Earth and Planetary Sciences},
year = {2005},
volume = {33},
pages = {443-459},
doi = {10.1146/annurev.earth.33.092203.122610}
}
|
||||||
| Williams, K. S. & Tarboton, D. G. | 1999 | The ABC's of snowmelt: a topographically factorized energy component snowmelt model. | Hydrological Processes 13 , 1905-1920 | snow; snowmelt runoff; snow hydrology; digital topography; digital elevation data | DOI |
|
| Abstract: Because of the crucial role snowmelt plays in many watersheds around the world, it is important to understand and accurately quantify the melt process. As such, numerous mathematical models attempting to describe and predict snowmelt have arisen. There are two main categories of models: conceptual index models and more intricate energy balance models. The index models, like the degree-day or radiation index models, are practical enough for use in large basins for operational purposes; while the energy balance models, though they are complicated and require large amounts of data, can represent the physics behind melt and give more accurate representations of the spatial distribution of melt within small research basins. The ABC model presented here attempts to bridge the gap between these two extremes by providing a simple yet physically justifiable method that uses elevation and radiation indices together with some measurements to distribute melt over a watershed. This new model separates the energy that causes snowmelt into three components: a spatially uniform component, a component that is proportional to elevation, and one that is proportional to solar illumination (which is determined by topography). Measurements of snowmelt at several topographically unique points (called index points) in a watershed are related to elevation and solar illumination through regression in order to factor the melt energy into the three separate components at each time step. The model is driven using inputs from snowmelt measurements at the index locations used to calibrate the regression at each time step. Then the spatial patterns of solar illumination and elevation are used to predict the spatial distribution of melt over the whole watershed. Field data supplemented with synthetically generated data is used to test the model. | ||||||
BibTeX:
@article{Williams1999HP,
author = {Williams, Kevin S. and Tarboton, David G.},
title = {The {ABC}'s of snowmelt: a topographically factorized energy component snowmelt model.},
journal = {Hydrological Processes},
year = {1999},
volume = {13},
pages = {1905-1920},
doi = {10.1002/(SICI)1099-1085(199909)13:12/13<1905::AID-HYP890>3.0.CO;2-}
}
|
||||||
| Wise, S. M. | 2000 | Assessing the quality for hydrological applications of digital elevation models derived from contours. | Hydrological Processes 14 (11) , 1909-1929 | DEM | drainage work; catchment; error; accuracy; DTM; DEM | DOI |
| Abstract: Digital elevation models (DEMs) are becoming increasingly important tools in hydrological research and in water resources management. The quality of DEMs, however, normally is reported simply as the root mean square error of elevation, a statistic that fails to capture the numerous sources of error in DEMs or to predict their effect on the result of using the DEM. This paper presents a review of other approaches to assessing DEM quality, and argues that a full assessment of DEM quality must focus on the accuracy and reliability of the final product of the DEM analysis. A number of DEMs for the Slapton Ley catchments in Devon derived from digitized contour data are compared in an initial assessment of their sustainability for use in hydrological work. Two are available for purchase from data suppliers, and five more were created using a variety of interpolation techniques in widely available geographical information system software. The different interpretation methods produce DEMs with different artefacts, although analyses of the distribution of elevation values, and visual techniques, suggested that none of these were of a particularly pronounced nature. The results of using the DEMs to derive drainage networks and catchment areas showed that at the broad scale there was a high level of agreement between the DEMs. There were, however, important differences of detail. For example, some DEMs predicted drainage lines that occasionally crossed the original contours. The results of calculating the TOPMODEL topographic index showed far more variation, because the index is calculated for each pixel in the area, rather than being an aggregate result derived from numerous pixels. The main conclusion was that care should always be taken to assess the quality of a DEM before attempting to use it, and that results should always be checked to ensure that they appear to be reasonable. | ||||||
BibTeX:
@article{wise2000hp,
author = {Wise, S. M.},
title = {Assessing the quality for hydrological applications of digital elevation models derived from contours.},
journal = {Hydrological Processes},
year = {2000},
volume = {14},
number = {11},
pages = {1909-1929},
doi = {10.1002/1099-1085(20000815/30)14:11/12<1909::AID-HYP45>3.0.CO;2-6}
}
|
||||||
| Wise, S. M. | 1998 | The effect of GIS interpolation errors on the use of digital elevation models in geomorphology. [BibTeX] |
Landform Monitoring, Modelling and Analysis. John Wiley & Sons, Inc., Chichester | DEM | ||
BibTeX:
@incollection{Wise1998book,
author = {Wise, S. M.},
title = {The effect of {GIS} interpolation errors on the use of digital elevation models in geomorphology.},
booktitle = {Landform Monitoring, Modelling and Analysis.},
publisher = {John Wiley \& Sons, Inc., Chichester},
year = {1998}
}
|
||||||
| Wood, J. D. | 1998 | Modelling the continuity of surface form using Digital Elevation Models. | Proceedings, 8th International Symposium on Spatial Data Handling , 725-36 | DEM | DEM ; scale; weighted surface network; morphometry; representation; | URL |
| Abstract: A new method of modelling surface form based the identification of a conic section's semi-axes is presented. It characterises surface behaviour over a local region rather than at a point. It is shown to produce significantly different results for calculations such as slope, aspect and surface flow direction. It is suggested that this method is more appropriate for characterisation of surfaces where continuity between neighbouring points in a DEM is important. An algorithm using the method is given, along with results of its implementation. It is shown to be appropriate for multi-scale surface specific feature identification as it allows users to 'filter' scales of interest. It is also demonstrated to be useful in the first stage of creating a topological weighted surface network. | ||||||
BibTeX:
@inproceedings{Wood1998ISSDH,
author = {Wood, Joseph D.},
title = {Modelling the continuity of surface form using Digital Elevation Models.},
booktitle = {Proceedings, 8th International Symposium on Spatial Data Handling},
year = {1998},
pages = {725-36},
url = {http://www.soi.city.ac.uk/~jwo/sdh98/}
}
|
||||||
| Wood, J. D. | 1996 | The Geomorphological Characterisation of Digital Elevation Models. | University of Leicester, UK | DEM | URL |
|
| Abstract: Techniques and issues are considered surrounding the characterisation of surface form represented by Digital Elevation Models (DEMs). A set of software tools suitable for use in a raster based Geographical Information System (GIS) is developed. Characterisation has three specific objectives, namely to identify spatial pattern, to identify scale dependency in form and to allow visualisation of results. An assessment is made of the characteristics of error in DEMs by identifying suitable quantitative measures and visualisation processes that may be enabled within a GIS. These are evaluated by contour threading a fractal surface and comparing four different spatial interpolations of the contours. The most effective error characterisations are found to be those that identify high frequency spatial pattern. Visualisation of spatiall arrangement of DEM error is used to develop a deterministic error model based on local surface slope and aspect. DEMs are parameterised using first and second derivatives of quadratic surfaces fitted over a range of scales. This offers advantages over traditional methods based on a 3 by 3 local window, as geomorphometric form can be characterised at any scale. Morphometric parameters are combined to give a feature classification that may also be applied over a range of scales. Multi-scale measurements are combined to give a feature membership function that describes how properties change with scale. These functions are visualised using modal and entropy measures of variability. An additional method of visualising scale dependency is suggested that graphically represents statistical measures of spatial pattern over a variety of spatial lags. This is found to be most appropriate for detecting structural anisotropy in a surface. Characterisation tools are evaluated by applying them to uncorrelated surfaces, fractal surfaces and Ordnance Survey DEMs of the Lake District, Peak District and Dartmoor. | ||||||
BibTeX:
@phdthesis{wood1996phd,
author = {Wood, Joseph D.},
title = {The Geomorphological Characterisation of Digital Elevation Models.},
school = {University of Leicester, UK},
year = {1996},
url = {http://www.soi.city.ac.uk/~jwo/phd/}
}
|
||||||
| Wood, J. D. & Fisher, P. F. | 1993 | Assessing Interpolation Accuracy in Elevation Models. [BibTeX] |
IEEE Computer Graphics & Applications 13 (2) , 48-56 | DEM | DEM, accuracy | |
BibTeX:
@article{wood1993ieeecga,
author = {Wood, Joseph D. and Fisher, Peter F.},
title = {Assessing Interpolation Accuracy in Elevation Models.},
journal = {IEEE Computer Graphics \& Applications},
year = {1993},
volume = {13},
number = {2},
pages = {48-56}
}
|
||||||
| Zadeh, L. A. | 1965 | Fuzzy sets. [BibTeX] |
Information and Control 8 , 338-353 | Uncertainty | ||
BibTeX:
@article{Zadeh1965IC,
author = {Zadeh, Lotfi A.},
title = {Fuzzy sets.},
journal = {Information and Control},
year = {1965},
volume = {8},
pages = {338-353}
}
|
||||||
| Zevenbergen, L. W. & Thorne, C. R. | 1987 | Quantitative analysis of land surface topography. [BibTeX] |
Earth Surface Processes and Landforms 12 , 47-56 | DEM | terrain analysis; topography; hydrological modelling; slope calculation; DEM ; derivatives; | |
BibTeX:
@article{zevenbergen1987espl,
author = {Zevenbergen, Lyle W. and Thorne, Colin R.},
title = {Quantitative analysis of land surface topography.},
journal = {Earth Surface Processes and Landforms},
year = {1987},
volume = {12},
pages = {47-56}
}
|
||||||
| Zhang, J. & Goodchild, M. F. | 2002 | Uncertainty in Geographical Information. [BibTeX] |
Research Monographs in Geographic Information Systems. Taylor & Francis, London | uncertainty | uncertainty; DEM ; GIS | |
BibTeX:
@incollection{Zhang2002tf,
author = {Zhang, Jingxiong and Goodchild, Michael F.},
title = {Uncertainty in Geographical Information.},
booktitle = {Research Monographs in Geographic Information Systems.},
publisher = {Taylor \& Francis, London},
year = {2002}
}
|
||||||
| Zhang, X., Drake, N. A., Wainwright, J. & Mulligan, M. | 1999 | Comparison of slope estimates from low resolution DEMs: scaling issues and a fractal method for their solution. | Earth Surface Processes and Landforms 24 (9) , 763-779 | DEM | slope; DEM resolution; fractal dimension; downscaling; regional to global scale; DEM; error; | URL |
| Abstract: Five different algorithms for calculating slope from digital elevation models (DEMs) have been compared from regional to global scales. Though different methods produce different results, the most significant outcome is that slope varies inversely with the DEM grid size. Thus, slopes estimated from coarse resolution data can be considered to produce significant underestimates of the true slope. A fractal theory is adapted to solve this problem. The variogram technique for the definition of fractal parameters is demonstrated to provide a relationship between slope and the spatial resolution of measurement. The variation of fractal parameters is discussed at various scales, and a model is developed to estimate the high resolution slope based on the coarse resolutionDEMby using fractal parameters. The fractal parameters are estimated from the standard deviation of elevation in a 3 x 3 window of the DEM to account for local variability in the surface. Standard deviation of elevation is found to be the most invariant property of different scale DEMs of the same area. The model is validated using different resolution DEMs in southern Spain and it is used to estimate the high resolution slope values at global scales based on a coarse resolutionDEM.The slopes estimated using the technique outlined are a significant improvement on those estimated directly from the coarse resolution data. Slopes estimated in this way allow the more effective use of available coarse resolution data in regional and global scale modelling studies. | ||||||
BibTeX:
@article{zhang1999espl,
author = {Zhang, Xiaoyang and Drake, Nick A. and Wainwright, John and Mulligan, Mark},
title = {Comparison of slope estimates from low resolution {DEMs}: scaling issues and a fractal method for their solution.},
journal = {Earth Surface Processes and Landforms},
year = {1999},
volume = {24},
number = {9},
pages = {763-779},
url = {http://www3.interscience.wiley.com/cgi-bin/abstract/63003652/ABSTRACT}
}
|
||||||
| Zhou, Q. & Liu, X. | 2004 | Analysis of errors of derived slope and aspect related to DEM data properties | Computers & Geoscience 30 , 369-378 | DEM | Digital terrain analysis; Error assessment; Digital terrain model; Slope; Aspect; Derivatives | URL |
| Abstract: One of the obvious sources of errors in digital terrain analysis (DTA) algorithms is that introduced by raster data structure employed by a digital elevation model (DEM). Because of its regular sample space and orientation, the DTA results often show significant octant ‘bias’, presenting obvious visual and numerical error patterns. Moreover, other DEM data properties may also introduce errors in slope and aspect computation, such as data precision and spatial resolution (i.e. grid interval). This paper reports an investigation on the accuracy of algorithms that derive slope and aspect measures from grid DEM. A quantitative methodology has been developed for objective and data-independent assessment of errors generated from the algorithms that extract surface morphological parameters such as slope and aspect from grid DEM. The generic approach is to use artificial surfaces that can be described by a mathematical model, thus the ‘true’ output value can be pre-determined to avoid uncertainty caused by uncontrollable data errors. Two mathematical surfaces were generated based on ellipsoid (representing convex slopes) and Gauss synthetic surface (representing complex slopes), and the theoretical ‘true’ value of the slope and aspect at any given point on the surfaces could be computed using mathematical inference. Based on these models, tests were made on the results from a number of algorithms for slope and aspect computation. Analysis has been undertaken to find out the spatial and statistical patterns of error distribution so that the influence of data precision, grid resolution, grid orientation and surface complexity can be quantified. | ||||||
BibTeX:
@article{zhou2004cg,
author = {Zhou, Qiming and Liu, Xuejun},
title = {Analysis of errors of derived slope and aspect related to {DEM} data properties},
journal = {Computers \& Geoscience},
year = {2004},
volume = {30},
pages = {369-378},
url = {http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6V7D-4BVP31M-6-1J&_cdi=5840&_user=946230&_orig=browse&_coverDate=05%2F31%2F2004&_sk=999699995&view=c&wchp=dGLbVzz-zSkzS&md5=e36958abf08cd4e77198a4826e76ea2c&ie=/sdarticle.pdf}
}
|
||||||
| Ziadat, F. M. | 2007 | Effect of Contour Intervals and Grid Cell Size on the Accuracy of DEMs and Slope Derivatives. | Transactions in GIS 11 (1) , 67-81 | DOI |
||
| Abstract: Digital Elevation Models (DEMs) are indispensable tools in many environmental and natural resource applications. DEMs are frequently derived from contour lines. The accuracy of such DEMs depends on different factors. This research investigates the effect of sampling density used to derive contours, vertical interval between contours (spacing), grid cell size of the DEM (resolution), terrain complexity, and spatial filtering on the accuracy of the DEM and the slope derivative. The study indicated different alternatives to achieve an acceptable accuracy depending on the contour interval, the DEM resolution and the complexity of the terrain. The effect of these factors on the accuracy of the DEM and the slope derivative was quantified using models that determine the level of accuracy (RMSE). The implementation of the models will guide users to select the best combination to improve the results in areas with similar topography. For areas with variable terrain complexity, the suggestion is to generate DEMs and slope at a suitable resolution for each terrain separately and then to merge the results to produce one final layer for the whole area. This will provide accurate estimates of elevation and slope, and subsequently improve the analyses that rely on these digital derivatives. | ||||||
BibTeX:
@article{Ziadat2007TIGIS,
author = {Ziadat, Feras M.},
title = {Effect of Contour Intervals and Grid Cell Size on the Accuracy of {DEM}s and Slope Derivatives.},
journal = {Transactions in GIS},
year = {2007},
volume = {11},
number = {1},
pages = {67-81},
doi = {10.1111/j.1467-9671.2007.01033.x}
}
|
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Felix Hebeler, University of Zurich, Dept. of Geography
Last modified: 07.05.2008 12:24