Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery
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 ba...
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2021
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ftdoajarticles:oai:doaj.org/article:ca402e05b3e7483ba52fe29fd21b443f 2023-05-15T16:27:46+02:00 Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery C. L. Benedek I. C. Willis 2021-04-01T00:00:00Z https://doi.org/10.5194/tc-15-1587-2021 https://doaj.org/article/ca402e05b3e7483ba52fe29fd21b443f EN eng Copernicus Publications https://tc.copernicus.org/articles/15/1587/2021/tc-15-1587-2021.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-15-1587-2021 1994-0416 1994-0424 https://doaj.org/article/ca402e05b3e7483ba52fe29fd21b443f The Cryosphere, Vol 15, Pp 1587-1606 (2021) Environmental sciences GE1-350 Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.5194/tc-15-1587-2021 2022-12-31T06:30:38Z 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 km 3 . 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 km 3 . 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. Article in Journal/Newspaper Greenland Ice Sheet The Cryosphere Directory of Open Access Journals: DOAJ Articles Greenland Rapid Lake ENVELOPE(177.619,177.619,52.064,52.064) Winter Lake ENVELOPE(-112.918,-112.918,64.484,64.484) The Cryosphere 15 3 1587 1606 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 C. L. Benedek I. C. Willis Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
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 km 3 . 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 km 3 . 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. |
format |
Article in Journal/Newspaper |
author |
C. L. Benedek I. C. Willis |
author_facet |
C. L. Benedek I. C. Willis |
author_sort |
C. L. Benedek |
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 Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-15-1587-2021 https://doaj.org/article/ca402e05b3e7483ba52fe29fd21b443f |
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 The Cryosphere |
genre_facet |
Greenland Ice Sheet The Cryosphere |
op_source |
The Cryosphere, Vol 15, Pp 1587-1606 (2021) |
op_relation |
https://tc.copernicus.org/articles/15/1587/2021/tc-15-1587-2021.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-15-1587-2021 1994-0416 1994-0424 https://doaj.org/article/ca402e05b3e7483ba52fe29fd21b443f |
op_doi |
https://doi.org/10.5194/tc-15-1587-2021 |
container_title |
The Cryosphere |
container_volume |
15 |
container_issue |
3 |
container_start_page |
1587 |
op_container_end_page |
1606 |
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1766017280408289280 |