Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects
In the ablation zone of land-terminating areas of the Greenland Ice Sheet, water pressures at the bed control seasonal and daily ice motion variability. During the melt season, large amounts of surface meltwater access the bed through moulins, which sustain an efficient channelized subglacial system...
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ftcopernicus:oai:publications.copernicus.org:tcd106231 2023-05-15T16:27:10+02:00 Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects Trunz, Celia Poinar, Kristin Andrews, Lauren C. Covington, Matthew D. Mejia, Jessica Gulley, Jason Siegel, Victoria 2022-09-20 application/pdf https://doi.org/10.5194/tc-2022-182 https://tc.copernicus.org/preprints/tc-2022-182/ eng eng doi:10.5194/tc-2022-182 https://tc.copernicus.org/preprints/tc-2022-182/ eISSN: 1994-0424 Text 2022 ftcopernicus https://doi.org/10.5194/tc-2022-182 2022-09-26T16:22:42Z In the ablation zone of land-terminating areas of the Greenland Ice Sheet, water pressures at the bed control seasonal and daily ice motion variability. During the melt season, large amounts of surface meltwater access the bed through moulins, which sustain an efficient channelized subglacial system. Water pressure within these subglacial channels can be inferred by measuring the hydraulic head within moulins. However, moulin head data are rare, and subglacial hydrology models that simulate water pressure fluctuations require water storage in moulins or subglacial channels. Neither the volume nor the location of such water storage is currently well constrained. Here, we use the Moulin Shape (MouSh) model, which quantifies time-evolving englacial storage, coupled with a subglacial channel model to simulate head measurements from a moulin in the Pâkitosq region in Greenland. We force the model with surface meltwater input calculated using field-acquired weather data. Our first-order simulations of moulin hydraulic head either over-predict the diurnal range of oscillation of the moulin head or require an unrealistically large moulin size to produce realistic head oscillation ranges. We find that to accurately match field observations of moulin head, additional subglacial water must be added to the system. We hypothesize that this additional `baseflow' represents strong subglacial network connectivity throughout the channelized system and is ultimately sourced from basal melt and non-local surface water inputs upstream. Text Greenland Ice Sheet Copernicus Publications: E-Journals Greenland |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
In the ablation zone of land-terminating areas of the Greenland Ice Sheet, water pressures at the bed control seasonal and daily ice motion variability. During the melt season, large amounts of surface meltwater access the bed through moulins, which sustain an efficient channelized subglacial system. Water pressure within these subglacial channels can be inferred by measuring the hydraulic head within moulins. However, moulin head data are rare, and subglacial hydrology models that simulate water pressure fluctuations require water storage in moulins or subglacial channels. Neither the volume nor the location of such water storage is currently well constrained. Here, we use the Moulin Shape (MouSh) model, which quantifies time-evolving englacial storage, coupled with a subglacial channel model to simulate head measurements from a moulin in the Pâkitosq region in Greenland. We force the model with surface meltwater input calculated using field-acquired weather data. Our first-order simulations of moulin hydraulic head either over-predict the diurnal range of oscillation of the moulin head or require an unrealistically large moulin size to produce realistic head oscillation ranges. We find that to accurately match field observations of moulin head, additional subglacial water must be added to the system. We hypothesize that this additional `baseflow' represents strong subglacial network connectivity throughout the channelized system and is ultimately sourced from basal melt and non-local surface water inputs upstream. |
format |
Text |
author |
Trunz, Celia Poinar, Kristin Andrews, Lauren C. Covington, Matthew D. Mejia, Jessica Gulley, Jason Siegel, Victoria |
spellingShingle |
Trunz, Celia Poinar, Kristin Andrews, Lauren C. Covington, Matthew D. Mejia, Jessica Gulley, Jason Siegel, Victoria Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects |
author_facet |
Trunz, Celia Poinar, Kristin Andrews, Lauren C. Covington, Matthew D. Mejia, Jessica Gulley, Jason Siegel, Victoria |
author_sort |
Trunz, Celia |
title |
Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects |
title_short |
Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects |
title_full |
Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects |
title_fullStr |
Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects |
title_full_unstemmed |
Observed and modeled moulin heads in the Pâkitsoq region of Greenland suggest subglacial channel network effects |
title_sort |
observed and modeled moulin heads in the pâkitsoq region of greenland suggest subglacial channel network effects |
publishDate |
2022 |
url |
https://doi.org/10.5194/tc-2022-182 https://tc.copernicus.org/preprints/tc-2022-182/ |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Ice Sheet |
genre_facet |
Greenland Ice Sheet |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-2022-182 https://tc.copernicus.org/preprints/tc-2022-182/ |
op_doi |
https://doi.org/10.5194/tc-2022-182 |
_version_ |
1766016251225702400 |