Cast shadows reveal changes in glacier surface elevation
Increased rates of glacier retreat and thinning need accurate local estimates of glacier elevation change to predict future changes in glacier runoff and their contribution to sea level rise. Glacier elevation change is typically derived from digital elevation models (DEMs) tied to surface change an...
Published in: | The Cryosphere |
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Copernicus Publications
2023
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00068507 2023-09-26T15:23:43+02:00 Cast shadows reveal changes in glacier surface elevation Pfau, Monika Veh, Georg Schwanghart, Wolfgang 2023-08 electronic https://doi.org/10.5194/tc-17-3535-2023 https://noa.gwlb.de/receive/cop_mods_00068507 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00066934/tc-17-3535-2023.pdf https://tc.copernicus.org/articles/17/3535/2023/tc-17-3535-2023.pdf eng eng Copernicus Publications The Cryosphere -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-17-3535-2023 https://noa.gwlb.de/receive/cop_mods_00068507 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00066934/tc-17-3535-2023.pdf https://tc.copernicus.org/articles/17/3535/2023/tc-17-3535-2023.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2023 ftnonlinearchiv https://doi.org/10.5194/tc-17-3535-2023 2023-08-27T23:20:34Z Increased rates of glacier retreat and thinning need accurate local estimates of glacier elevation change to predict future changes in glacier runoff and their contribution to sea level rise. Glacier elevation change is typically derived from digital elevation models (DEMs) tied to surface change analysis from satellite imagery. Yet, the rugged topography in mountain regions can cast shadows onto glacier surfaces, making it difficult to detect local glacier elevation changes in remote areas. A rather untapped resource comprises precise, time-stamped metadata on the solar position and angle in satellite images. These data are useful for simulating shadows from a given DEM. Accordingly, any differences in shadow length between simulated and mapped shadows in satellite images could indicate a change in glacier elevation relative to the acquisition date of the DEM. We tested this hypothesis at five selected glaciers with long-term monitoring programmes. For each glacier, we projected cast shadows onto the glacier surface from freely available DEMs and compared simulated shadows to cast shadows mapped from ∼40 years of Landsat images. We validated the relative differences with geodetic measurements of glacier elevation change where these shadows occurred. We find that shadow-derived glacier elevation changes are consistent with independent photogrammetric and geodetic surveys in shaded areas. Accordingly, a shadow cast on Baltoro Glacier (the Karakoram, Pakistan) suggests no changes in elevation between 1987 and 2020, while shadows on Great Aletsch Glacier (Switzerland) point to negative thinning rates of about 1 m yr−1 in our sample. Our estimates of glacier elevation change are tied to occurrence of mountain shadows and may help complement field campaigns in regions that are difficult to access. This information can be vital to quantify possibly varying elevation-dependent changes in the accumulation or ablation zone of a given glacier. Shadow-based retrieval of glacier elevation changes hinges on the precision of ... Article in Journal/Newspaper The Cryosphere Niedersächsisches Online-Archiv NOA The Cryosphere 17 8 3535 3551 |
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English |
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article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Pfau, Monika Veh, Georg Schwanghart, Wolfgang Cast shadows reveal changes in glacier surface elevation |
topic_facet |
article Verlagsveröffentlichung |
description |
Increased rates of glacier retreat and thinning need accurate local estimates of glacier elevation change to predict future changes in glacier runoff and their contribution to sea level rise. Glacier elevation change is typically derived from digital elevation models (DEMs) tied to surface change analysis from satellite imagery. Yet, the rugged topography in mountain regions can cast shadows onto glacier surfaces, making it difficult to detect local glacier elevation changes in remote areas. A rather untapped resource comprises precise, time-stamped metadata on the solar position and angle in satellite images. These data are useful for simulating shadows from a given DEM. Accordingly, any differences in shadow length between simulated and mapped shadows in satellite images could indicate a change in glacier elevation relative to the acquisition date of the DEM. We tested this hypothesis at five selected glaciers with long-term monitoring programmes. For each glacier, we projected cast shadows onto the glacier surface from freely available DEMs and compared simulated shadows to cast shadows mapped from ∼40 years of Landsat images. We validated the relative differences with geodetic measurements of glacier elevation change where these shadows occurred. We find that shadow-derived glacier elevation changes are consistent with independent photogrammetric and geodetic surveys in shaded areas. Accordingly, a shadow cast on Baltoro Glacier (the Karakoram, Pakistan) suggests no changes in elevation between 1987 and 2020, while shadows on Great Aletsch Glacier (Switzerland) point to negative thinning rates of about 1 m yr−1 in our sample. Our estimates of glacier elevation change are tied to occurrence of mountain shadows and may help complement field campaigns in regions that are difficult to access. This information can be vital to quantify possibly varying elevation-dependent changes in the accumulation or ablation zone of a given glacier. Shadow-based retrieval of glacier elevation changes hinges on the precision of ... |
format |
Article in Journal/Newspaper |
author |
Pfau, Monika Veh, Georg Schwanghart, Wolfgang |
author_facet |
Pfau, Monika Veh, Georg Schwanghart, Wolfgang |
author_sort |
Pfau, Monika |
title |
Cast shadows reveal changes in glacier surface elevation |
title_short |
Cast shadows reveal changes in glacier surface elevation |
title_full |
Cast shadows reveal changes in glacier surface elevation |
title_fullStr |
Cast shadows reveal changes in glacier surface elevation |
title_full_unstemmed |
Cast shadows reveal changes in glacier surface elevation |
title_sort |
cast shadows reveal changes in glacier surface elevation |
publisher |
Copernicus Publications |
publishDate |
2023 |
url |
https://doi.org/10.5194/tc-17-3535-2023 https://noa.gwlb.de/receive/cop_mods_00068507 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00066934/tc-17-3535-2023.pdf https://tc.copernicus.org/articles/17/3535/2023/tc-17-3535-2023.pdf |
genre |
The Cryosphere |
genre_facet |
The Cryosphere |
op_relation |
The Cryosphere -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-17-3535-2023 https://noa.gwlb.de/receive/cop_mods_00068507 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00066934/tc-17-3535-2023.pdf https://tc.copernicus.org/articles/17/3535/2023/tc-17-3535-2023.pdf |
op_rights |
https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/tc-17-3535-2023 |
container_title |
The Cryosphere |
container_volume |
17 |
container_issue |
8 |
container_start_page |
3535 |
op_container_end_page |
3551 |
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1778150011535622144 |