scholarly journals Extracting and visualising glacial ice flow directions from Digital Elevation Models using greyscale thinning and directional trend analyses

2021 ◽  
Vol 147 ◽  
pp. 104677
Author(s):  
Artūrs Putniņš ◽  
Håvard Tveite
Keyword(s):  
Digital Elevation Models ◽  
Ice Flow ◽  
Glacial Ice ◽  
Trend Analyses ◽  
Digital Elevation ◽  
Flow Directions ◽  
Directional Trend

scholarly journals Retaining Relative Height Information: An Enhanced Technique for Depression Treatment in Digital Elevation Models

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3347
Author(s):  
Bo Chen ◽  
Chunying Ma ◽  
Yao Xiao ◽  
Hanxin Gao ◽  
Peijun Shi ◽  
...  
Keyword(s):  
Complex Terrain ◽  
Digital Elevation Models ◽  
Treatment Algorithm ◽  
Depression Treatment ◽  
Direct Flow ◽  
Original Algorithm ◽  
Drainage Networks ◽  
Digital Elevation ◽  
Flow Directions ◽  
The Difference

This study presents an enhanced variant of the priority-flood based algorithm proposed by Wang and Liu for treating depressions in digital elevation models (DEMs). The enhanced variant redefines spill elevation, the key concept of the original algorithm, as the lowest elevation that a pixel needs to have to ensure a non-ascending path toward the border of the DEM, plus the larger of a small number (~0.001) and the difference between the unaltered elevation values of the focal pixel and its immediate downhill neighbor. This redefinition is adopted to obtain an intermediate elevation surface to direct flow and ultimately to carve the original DEM. Each carving starts from a depression bottom and propagates downstream until a downhill cell is guaranteed in the original DEM. Tests of these algorithms on a complex terrain of the 260,000 km2 Sichuan structural basin in China shows that the enhanced algorithm maximally preserves the original flow directions and extracts realistic drainage networks. Retaining the relative heights, and therefore flow directions, of cells within depressions allows the new algorithm to offer a depressionless DEM with small modification of its origin for further hydrologic applications. The enhanced depression treatment algorithm is provided as the freely available tool BNUSinkRemv.

scholarly journals Improved GNSS-R bi-static altimetry and independent digital elevation models of Greenland and Antarctica from TechDemoSat-1

2020 ◽  
Vol 14 (6) ◽  
pp. 1909-1917 ◽  
Author(s):  
Jessica Cartwright ◽  
Christopher J. Banks ◽  
Meric Srokosz
Keyword(s):  
Digital Elevation Models ◽  
Global Navigation Satellite Systems ◽  
Glacial Ice ◽  
Satellite Systems ◽  
Digital Elevation ◽  
Future Potential ◽  
The Uk ◽  
Global Navigation Satellite ◽  
The Antarctic ◽  
Mean Square Errors

Abstract. Improved digital elevation models (DEMs) of the Antarctic and Greenland ice sheets are presented, which have been derived from Global Navigation Satellite Systems-Reflectometry (GNSS-R). This builds on a previous study (Cartwright et al., 2018) using GNSS-R to derive an Antarctic DEM but uses improved processing and an additional 13 months of measurements, totalling 46 months of data from the UK TechDemoSat-1 satellite. A median bias of under 10 m and root-mean-square errors (RMSEs) of under 53 m for the Antarctic and 166 m for Greenland are obtained, as compared to existing DEMs. The results represent, compared to the earlier study, a halving of the median bias to 9 m, an improvement in coverage of 18 %, and a 4 times higher spatial resolution (now gridded at 25 km). In addition, these are the first published satellite altimetry measurements of the region surrounding the South Pole. Comparisons south of 88∘ S yield RMSEs of less than 33 m when compared to NASA's Operation IceBridge measurements. Differences between DEMs are explored, the limitations of the technique are noted, and the future potential of GNSS-R for glacial ice studies is discussed.

scholarly journals Interferometric swath processing of Cryosat-2 data for glacial ice topography

2013 ◽  
Vol 7 (3) ◽  
pp. 3133-3162 ◽  
Author(s):  
L. Gray ◽  
D. Burgess ◽  
L. Copland ◽  
R. Cullen ◽  
N. Galin ◽  
...  
Keyword(s):  
Digital Elevation Models ◽  
Main Beam ◽  
Glacial Ice ◽  
Ice Cap ◽  
Digital Elevation ◽  
Interferometric Phase ◽  
Elevation Data ◽  
Devon Ice Cap ◽  
Cross Track ◽  
Level 2

Abstract. We have derived Digital Elevation Models (DEMs) over the western part of the Devon Ice Cap in Nunavut Canada using "swath processing" of interferometric data collected by Cryosat 2 between February 2011 and January 2012. In the standard ESA "SARIn" level 2 (L2) data product the interferometric mode is used to map the cross-track position and elevation of the "point-of-closest-approach" (POCA) in sloping glacial terrain. However, in this work we explore the extent to which the phase of the returns in the intermediate L1b product can also be used to map the heights of time delayed footprints beyond the POCA. We show that there is a range of average cross-track slopes (~0.5° to ~2°) for which the returns will be dominated by those beneath the satellite in the main beam of the antenna and that the resulting interferometric phase allows mapping of heights in the delayed range window beyond the POCA. In this way a swath of elevation data is mapped allowing the creation of Digital Elevation Models (DEMs) from a sequence of L1b SARIn Cryosat-2 data takes. Comparison of the Devon results with airborne scanning laser data showed a mean difference of order a meter with a standard deviation < 1 m. The limitations of swath processing, which generates almost 2 orders of magnitude more data than traditional radar altimetry, are explored through simulation, and the strengths and weaknesses of the technique are discussed.

scholarly journals Blieschow on Jasmund &#8211; geomorphology and glacigenic landforms: keys to understanding the deformation chronology of Jasmund

2019 ◽  
Vol 2 ◽  
pp. 11-17 ◽  
Author(s):  
Anna Gehrmann ◽  
Chris Harding
Keyword(s):  
Genetic Model ◽  
Digital Elevation Models ◽  
Flow Patterns ◽  
Ice Flow ◽  
Geomorphological Mapping ◽  
Digital Elevation ◽  
Late Weichselian

Abstract. The late Weichselian glacitectonic framework of the Jasmund peninsula forms surface expressions of subparallel ridges and elongated valleys in between. Geomorphological mapping and landform analyses based on lidar-derived digital elevation models (DEMs) give rise to a revised genetic model for Jasmund, including three evolutional stages that are characterised by different ice flow patterns.

Digital Elevation Models

10.1596/34445 ◽  
2020 ◽  
Author(s):  
Louise Croneborg ◽  
Keiko Saito ◽  
Michel Matera ◽  
Don McKeown ◽  
Jan van Aardt
Keyword(s):  
Digital Elevation Models ◽  
Digital Elevation
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