Challenges in predicting Greenland supraglacial lake drainages at the regional scale
A leading hypothesis for the mechanism of fast supraglacial lake drainages is that transient extensional stresses briefly allow crevassing in otherwise-compressive ice flow regimes. Lake water can then hydrofracture the crevasse to the base of the ice sheet, and river inputs can maintain this connec...
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ftcopernicus:oai:publications.copernicus.org:tcd89372 2023-05-15T16:28:19+02:00 Challenges in predicting Greenland supraglacial lake drainages at the regional scale Poinar, Kristin Andrews, Lauren C. 2020-10-05 application/pdf https://doi.org/10.5194/tc-2020-251 https://tc.copernicus.org/preprints/tc-2020-251/ eng eng doi:10.5194/tc-2020-251 https://tc.copernicus.org/preprints/tc-2020-251/ eISSN: 1994-0424 Text 2020 ftcopernicus https://doi.org/10.5194/tc-2020-251 2020-10-12T16:22:14Z A leading hypothesis for the mechanism of fast supraglacial lake drainages is that transient extensional stresses briefly allow crevassing in otherwise-compressive ice flow regimes. Lake water can then hydrofracture the crevasse to the base of the ice sheet, and river inputs can maintain this connection as a moulin. If future ice-sheet models are to accurately represent moulins, we must understand their formation processes, timescales, and locations. Here, we use remote-sensing velocity products to constrain the relationship between strain rates and lake drainages across ~ 1600 km 2 in Pâkitsoq, western Greenland, between 2002–2019. We find significantly more-extensional background strain rates at moulins associated with fast-draining lakes than at slow-draining or non-draining lake moulins. We test whether moulins in more-extensional background settings drain their lakes earlier, but find insignificant correlation. To investigate the frequency that strain-rate transients are associated with fast lake drainage, we examined Landsat-derived strain rates over 16- and 32-day periods at moulins associated with 240 fast lake drainage events over 18 years. A low signal-to-noise ratio, the presence of water, and the multi-week repeat cycle obscured any resolution of the hypothesized transient strain rates. Our results support the hypothesis that transient strain rates drive fast lake drainages. However, the current generation of ice-sheet velocity products, even when stacked across hundreds of fast lake drainages, cannot resolve these transients. Thus, observational progress in understanding lake drainage initiation will rely on field-based tools such as GPS networks and photogrammetry. Text Greenland Ice Sheet Copernicus Publications: E-Journals Fast Lake ENVELOPE(-108.251,-108.251,59.983,59.983) Greenland |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
A leading hypothesis for the mechanism of fast supraglacial lake drainages is that transient extensional stresses briefly allow crevassing in otherwise-compressive ice flow regimes. Lake water can then hydrofracture the crevasse to the base of the ice sheet, and river inputs can maintain this connection as a moulin. If future ice-sheet models are to accurately represent moulins, we must understand their formation processes, timescales, and locations. Here, we use remote-sensing velocity products to constrain the relationship between strain rates and lake drainages across ~ 1600 km 2 in Pâkitsoq, western Greenland, between 2002–2019. We find significantly more-extensional background strain rates at moulins associated with fast-draining lakes than at slow-draining or non-draining lake moulins. We test whether moulins in more-extensional background settings drain their lakes earlier, but find insignificant correlation. To investigate the frequency that strain-rate transients are associated with fast lake drainage, we examined Landsat-derived strain rates over 16- and 32-day periods at moulins associated with 240 fast lake drainage events over 18 years. A low signal-to-noise ratio, the presence of water, and the multi-week repeat cycle obscured any resolution of the hypothesized transient strain rates. Our results support the hypothesis that transient strain rates drive fast lake drainages. However, the current generation of ice-sheet velocity products, even when stacked across hundreds of fast lake drainages, cannot resolve these transients. Thus, observational progress in understanding lake drainage initiation will rely on field-based tools such as GPS networks and photogrammetry. |
format |
Text |
author |
Poinar, Kristin Andrews, Lauren C. |
spellingShingle |
Poinar, Kristin Andrews, Lauren C. Challenges in predicting Greenland supraglacial lake drainages at the regional scale |
author_facet |
Poinar, Kristin Andrews, Lauren C. |
author_sort |
Poinar, Kristin |
title |
Challenges in predicting Greenland supraglacial lake drainages at the regional scale |
title_short |
Challenges in predicting Greenland supraglacial lake drainages at the regional scale |
title_full |
Challenges in predicting Greenland supraglacial lake drainages at the regional scale |
title_fullStr |
Challenges in predicting Greenland supraglacial lake drainages at the regional scale |
title_full_unstemmed |
Challenges in predicting Greenland supraglacial lake drainages at the regional scale |
title_sort |
challenges in predicting greenland supraglacial lake drainages at the regional scale |
publishDate |
2020 |
url |
https://doi.org/10.5194/tc-2020-251 https://tc.copernicus.org/preprints/tc-2020-251/ |
long_lat |
ENVELOPE(-108.251,-108.251,59.983,59.983) |
geographic |
Fast Lake Greenland |
geographic_facet |
Fast Lake Greenland |
genre |
Greenland Ice Sheet |
genre_facet |
Greenland Ice Sheet |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-2020-251 https://tc.copernicus.org/preprints/tc-2020-251/ |
op_doi |
https://doi.org/10.5194/tc-2020-251 |
_version_ |
1766017961601007616 |