Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery
<jats:p>Abstract. Surface lakes on the Greenland Ice Sheet play a key role in its surface mass balance, hydrology and biogeochemistry. They often drain rapidly in the summer via hydrofracture, which delivers lake water to the ice sheet base over timescales of hours to days and then can allow m...
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ftunivcam:oai:www.repository.cam.ac.uk:1810/319511 2024-01-14T10:07:17+01:00 Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery Benedek, CL Willis, IC 2021 application/pdf https://www.repository.cam.ac.uk/handle/1810/319511 https://doi.org/10.17863/CAM.66632 eng eng Copernicus GmbH http://dx.doi.org/10.5194/tc-15-1587-2021 Cryosphere https://doi.org/10.17863/CAM.66094 https://www.repository.cam.ac.uk/handle/1810/319511 doi:10.17863/CAM.66632 Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/ 37 Earth Sciences 3709 Physical Geography and Environmental Geoscience 3705 Geology 14 Life Below Water Article 2021 ftunivcam https://doi.org/10.17863/CAM.6663210.17863/CAM.66094 2023-12-21T23:21:05Z <jats:p>Abstract. Surface lakes on the Greenland Ice Sheet play a key role in its surface mass balance, hydrology and biogeochemistry. They often drain rapidly in the summer via hydrofracture, which delivers lake water to the ice sheet base over timescales of hours to days and then can allow meltwater to reach the base for the rest of the summer. Rapid lake drainage, therefore, influences subglacial drainage evolution; water pressures; ice flow; biogeochemical activity; and ultimately the delivery of water, sediments and nutrients to the ocean. It has generally been assumed that rapid lake drainage events are confined to the summer, as this is typically when observations are made using satellite optical imagery. Here we develop a method to quantify backscatter changes in satellite radar imagery, which we use to document the drainage of six different lakes during three winters (2014/15, 2015/16 and 2016/17) in fast-flowing parts of the Greenland Ice Sheet. Analysis of optical imagery from before and after the three winters supports the radar-based evidence for winter lake drainage events and also provides estimates of lake drainage volumes, which range between 0.000046 ± 0.000017 and 0.0200 ± 0.002817 km3. For three of the events, optical imagery allows repeat photoclinometry (shape from shading) calculations to be made showing mean vertical collapse of the lake surfaces ranging between 1.21 ± 1.61 and 7.25 ± 1.61 m and drainage volumes of 0.002 ± 0.002968 to 0.044 ± 0.009858 km3. For one of these three, time-stamped ArcticDEM strips allow for DEM differencing, which demonstrates a mean collapse depth of 2.17 ± 0.28 m across the lake area. The findings show that lake drainage can occur in the winter in the absence of active surface melt and notable ice flow acceleration, which may have important implications for subglacial hydrology and biogeochemical processes. </jats:p> Corinne L. Benedek is funded by the Howard Research Studentship through Sidney Sussex College and the Cambridge Trust. Ian C. ... Article in Journal/Newspaper Greenland Ice Sheet Apollo - University of Cambridge Repository Greenland Rapid Lake ENVELOPE(177.619,177.619,52.064,52.064) Winter Lake ENVELOPE(-112.918,-112.918,64.484,64.484) |
institution |
Open Polar |
collection |
Apollo - University of Cambridge Repository |
op_collection_id |
ftunivcam |
language |
English |
topic |
37 Earth Sciences 3709 Physical Geography and Environmental Geoscience 3705 Geology 14 Life Below Water |
spellingShingle |
37 Earth Sciences 3709 Physical Geography and Environmental Geoscience 3705 Geology 14 Life Below Water Benedek, CL Willis, IC Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery |
topic_facet |
37 Earth Sciences 3709 Physical Geography and Environmental Geoscience 3705 Geology 14 Life Below Water |
description |
<jats:p>Abstract. Surface lakes on the Greenland Ice Sheet play a key role in its surface mass balance, hydrology and biogeochemistry. They often drain rapidly in the summer via hydrofracture, which delivers lake water to the ice sheet base over timescales of hours to days and then can allow meltwater to reach the base for the rest of the summer. Rapid lake drainage, therefore, influences subglacial drainage evolution; water pressures; ice flow; biogeochemical activity; and ultimately the delivery of water, sediments and nutrients to the ocean. It has generally been assumed that rapid lake drainage events are confined to the summer, as this is typically when observations are made using satellite optical imagery. Here we develop a method to quantify backscatter changes in satellite radar imagery, which we use to document the drainage of six different lakes during three winters (2014/15, 2015/16 and 2016/17) in fast-flowing parts of the Greenland Ice Sheet. Analysis of optical imagery from before and after the three winters supports the radar-based evidence for winter lake drainage events and also provides estimates of lake drainage volumes, which range between 0.000046 ± 0.000017 and 0.0200 ± 0.002817 km3. For three of the events, optical imagery allows repeat photoclinometry (shape from shading) calculations to be made showing mean vertical collapse of the lake surfaces ranging between 1.21 ± 1.61 and 7.25 ± 1.61 m and drainage volumes of 0.002 ± 0.002968 to 0.044 ± 0.009858 km3. For one of these three, time-stamped ArcticDEM strips allow for DEM differencing, which demonstrates a mean collapse depth of 2.17 ± 0.28 m across the lake area. The findings show that lake drainage can occur in the winter in the absence of active surface melt and notable ice flow acceleration, which may have important implications for subglacial hydrology and biogeochemical processes. </jats:p> Corinne L. Benedek is funded by the Howard Research Studentship through Sidney Sussex College and the Cambridge Trust. Ian C. ... |
format |
Article in Journal/Newspaper |
author |
Benedek, CL Willis, IC |
author_facet |
Benedek, CL Willis, IC |
author_sort |
Benedek, CL |
title |
Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery |
title_short |
Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery |
title_full |
Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery |
title_fullStr |
Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery |
title_full_unstemmed |
Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery |
title_sort |
winter drainage of surface lakes on the greenland ice sheet from sentinel-1 sar imagery |
publisher |
Copernicus GmbH |
publishDate |
2021 |
url |
https://www.repository.cam.ac.uk/handle/1810/319511 https://doi.org/10.17863/CAM.66632 |
long_lat |
ENVELOPE(177.619,177.619,52.064,52.064) ENVELOPE(-112.918,-112.918,64.484,64.484) |
geographic |
Greenland Rapid Lake Winter Lake |
geographic_facet |
Greenland Rapid Lake Winter Lake |
genre |
Greenland Ice Sheet |
genre_facet |
Greenland Ice Sheet |
op_relation |
https://doi.org/10.17863/CAM.66094 https://www.repository.cam.ac.uk/handle/1810/319511 doi:10.17863/CAM.66632 |
op_rights |
Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.17863/CAM.6663210.17863/CAM.66094 |
_version_ |
1788061700594860032 |