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...
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Copernicus Publications
2023
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ftdoajarticles:oai:doaj.org/article:0d3ef9a8d1b140ff9be154f2183f0206 2023-09-26T15:23:43+02:00 Cast shadows reveal changes in glacier surface elevation M. Pfau G. Veh W. Schwanghart 2023-08-01T00:00:00Z https://doi.org/10.5194/tc-17-3535-2023 https://doaj.org/article/0d3ef9a8d1b140ff9be154f2183f0206 EN eng Copernicus Publications https://tc.copernicus.org/articles/17/3535/2023/tc-17-3535-2023.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-17-3535-2023 1994-0416 1994-0424 https://doaj.org/article/0d3ef9a8d1b140ff9be154f2183f0206 The Cryosphere, Vol 17, Pp 3535-3551 (2023) Environmental sciences GE1-350 Geology QE1-996.5 article 2023 ftdoajarticles https://doi.org/10.5194/tc-17-3535-2023 2023-08-27T00:36:49Z 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 Directory of Open Access Journals: DOAJ Articles The Cryosphere 17 8 3535 3551 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
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ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
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Environmental sciences GE1-350 Geology QE1-996.5 M. Pfau G. Veh W. Schwanghart Cast shadows reveal changes in glacier surface elevation |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
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 |
M. Pfau G. Veh W. Schwanghart |
author_facet |
M. Pfau G. Veh W. Schwanghart |
author_sort |
M. Pfau |
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://doaj.org/article/0d3ef9a8d1b140ff9be154f2183f0206 |
genre |
The Cryosphere |
genre_facet |
The Cryosphere |
op_source |
The Cryosphere, Vol 17, Pp 3535-3551 (2023) |
op_relation |
https://tc.copernicus.org/articles/17/3535/2023/tc-17-3535-2023.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-17-3535-2023 1994-0416 1994-0424 https://doaj.org/article/0d3ef9a8d1b140ff9be154f2183f0206 |
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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1778150009791840256 |