Variability of Basal Meltwater Generation During Winter, Western Greenland Ice Sheet
Basal sliding in the ablation zone of the Greenland Ice Sheet is closely associated with water from surface melt introduced to the bed in summer, yet melting of basal ice also generates subglacial water year-round. Assessments of basal melt rely on modelling with results strongly dependent upon assu...
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ftcopernicus:oai:publications.copernicus.org:tcd95326 2023-05-15T16:26:39+02:00 Variability of Basal Meltwater Generation During Winter, Western Greenland Ice Sheet Harper, Joel Meierbachtol, Toby Humphrey, Neil Saito, Jun Stansberry, Aidan 2021-06-28 application/pdf https://doi.org/10.5194/tc-2021-179 https://tc.copernicus.org/preprints/tc-2021-179/ eng eng doi:10.5194/tc-2021-179 https://tc.copernicus.org/preprints/tc-2021-179/ eISSN: 1994-0424 Text 2021 ftcopernicus https://doi.org/10.5194/tc-2021-179 2021-07-05T16:22:18Z Basal sliding in the ablation zone of the Greenland Ice Sheet is closely associated with water from surface melt introduced to the bed in summer, yet melting of basal ice also generates subglacial water year-round. Assessments of basal melt rely on modelling with results strongly dependent upon assumptions with poor observational constraint. Here we use surface and borehole measurements to investigate the generation and fate of basal meltwater in the ablation zone of Isunnguata Sermia basin, Western Greenland. The observational data are used to constrain estimates of the heat and water balances, providing insights into subglacial hydrology during the winter months when surface melt is minimal or non-existent. Despite relatively slow ice flow speeds during winter, the basal meltwater generation from sliding friction remains many fold greater than that due to geothermal heat flux. A steady acceleration of ice flow over the winter period at our borehole sites can cause the rate of basal water generation to increase by up to 20 %. Borehole measurements show high but steady basal water pressure, rather than monotonically increasing pressure. Ice and groundwater sinks for water do not likely have sufficient capacity to accommodate the meltwater generated in winter. Analysis of basal cavity dynamics suggests that cavity opening associated with flow acceleration likely accommodates only a portion of the basal meltwater, implying a residual is routed to the terminus through a poorly connected drainage system. A forcing from cavity expansion at high pressure may explain observations of winter acceleration in Western Greenland. Text Greenland Ice Sheet Copernicus Publications: E-Journals Greenland Isunnguata Sermia ENVELOPE(-50.167,-50.167,67.183,67.183) |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
Basal sliding in the ablation zone of the Greenland Ice Sheet is closely associated with water from surface melt introduced to the bed in summer, yet melting of basal ice also generates subglacial water year-round. Assessments of basal melt rely on modelling with results strongly dependent upon assumptions with poor observational constraint. Here we use surface and borehole measurements to investigate the generation and fate of basal meltwater in the ablation zone of Isunnguata Sermia basin, Western Greenland. The observational data are used to constrain estimates of the heat and water balances, providing insights into subglacial hydrology during the winter months when surface melt is minimal or non-existent. Despite relatively slow ice flow speeds during winter, the basal meltwater generation from sliding friction remains many fold greater than that due to geothermal heat flux. A steady acceleration of ice flow over the winter period at our borehole sites can cause the rate of basal water generation to increase by up to 20 %. Borehole measurements show high but steady basal water pressure, rather than monotonically increasing pressure. Ice and groundwater sinks for water do not likely have sufficient capacity to accommodate the meltwater generated in winter. Analysis of basal cavity dynamics suggests that cavity opening associated with flow acceleration likely accommodates only a portion of the basal meltwater, implying a residual is routed to the terminus through a poorly connected drainage system. A forcing from cavity expansion at high pressure may explain observations of winter acceleration in Western Greenland. |
format |
Text |
author |
Harper, Joel Meierbachtol, Toby Humphrey, Neil Saito, Jun Stansberry, Aidan |
spellingShingle |
Harper, Joel Meierbachtol, Toby Humphrey, Neil Saito, Jun Stansberry, Aidan Variability of Basal Meltwater Generation During Winter, Western Greenland Ice Sheet |
author_facet |
Harper, Joel Meierbachtol, Toby Humphrey, Neil Saito, Jun Stansberry, Aidan |
author_sort |
Harper, Joel |
title |
Variability of Basal Meltwater Generation During Winter, Western Greenland Ice Sheet |
title_short |
Variability of Basal Meltwater Generation During Winter, Western Greenland Ice Sheet |
title_full |
Variability of Basal Meltwater Generation During Winter, Western Greenland Ice Sheet |
title_fullStr |
Variability of Basal Meltwater Generation During Winter, Western Greenland Ice Sheet |
title_full_unstemmed |
Variability of Basal Meltwater Generation During Winter, Western Greenland Ice Sheet |
title_sort |
variability of basal meltwater generation during winter, western greenland ice sheet |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-2021-179 https://tc.copernicus.org/preprints/tc-2021-179/ |
long_lat |
ENVELOPE(-50.167,-50.167,67.183,67.183) |
geographic |
Greenland Isunnguata Sermia |
geographic_facet |
Greenland Isunnguata Sermia |
genre |
Greenland Ice Sheet |
genre_facet |
Greenland Ice Sheet |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-2021-179 https://tc.copernicus.org/preprints/tc-2021-179/ |
op_doi |
https://doi.org/10.5194/tc-2021-179 |
_version_ |
1766015588488970240 |