Modeling and Measuring Water Level Fluctuations in the Greenland Ice Sheet: How Moulin Life Cycle and Shape can Inform us on the Subglacial Drainage System.
In the ablation zone of land terminating sectors of the Greenland Ice Sheet (GrIS), water pressures at the bed control ice motion variability on diurnal and seasonal timescales. During the melt season, large volumes of surface meltwater access the ice-bed interface through moulins.Moulins are large...
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ftunivarkansas:oai:scholarworks.uark.edu:etd-5676 2023-11-12T04:10:27+01:00 Modeling and Measuring Water Level Fluctuations in the Greenland Ice Sheet: How Moulin Life Cycle and Shape can Inform us on the Subglacial Drainage System. Trunz, Celia 2021-07-01T07:00:00Z application/pdf https://scholarworks.uark.edu/etd/4126 https://scholarworks.uark.edu/context/etd/article/5676/viewcontent/Trunz_uark_0011A_14398.pdf unknown ScholarWorks@UARK https://scholarworks.uark.edu/etd/4126 https://scholarworks.uark.edu/context/etd/article/5676/viewcontent/Trunz_uark_0011A_14398.pdf Graduate Theses and Dissertations Ablation area Arctic Cryosphere Glacial hydrology Glaciology Polar region Climate Geomorphology Hydrology text 2021 ftunivarkansas 2023-10-30T09:52:34Z In the ablation zone of land terminating sectors of the Greenland Ice Sheet (GrIS), water pressures at the bed control ice motion variability on diurnal and seasonal timescales. During the melt season, large volumes of surface meltwater access the ice-bed interface through moulins.Moulins are large vertical shafts that connect the supraglacial and subglacial drainage systems. Moulins form when a crevasse intersects a surface meltwater source that can drive hydrofracture to the bed of the ice sheet. Upon reaching the bed, meltwater can establish and sustain an efficient, channelized drainage system. Due to the technical impossibility of physically exploring underwater passages beneath the GrIS, the subglacial drainage system must be studied through geophysical methods. To date, measurements of water level variability within moulins and boreholes have proved to be critical for constraining models. However, direct hydrologic measurements from the GrIS are sparse, due to the remoteness and harsh conditions of the ice sheet. The work presented in this dissertation combines simple physically based mathematical models with direct measurements from the ablation portion of Sermeq Avannarleq, in west Greenland to advance our understanding of the influence of moulin geometry and life span on glacier dynamics. In Chapter 2, I investigate the moulin life cycle within several neighboring surface catchments within the GrIS ablation zone. A combination of remote sensing and ground observations of moulin locations over two to three years reveals an annual pattern of systematic formation and abandonment of moulins after they are advected down-glacier.In Chapter 3, I use a modified single conduit model to explore the role of moulin shape and size on hydraulic head variability within moulins. This model shows that only the englacial storage capacity within the range of water level fluctuations affects the oscillation range of moulin hydraulic head, which controls subglacial channel water pressure dynamics. Further, the model shows ... Text arctic cryosphere Arctic glacier Greenland Ice Sheet University of Arkansas: ScholarWorks@UARK Arctic Avannarleq ENVELOPE(-49.100,-49.100,62.133,62.133) Greenland Sermeq Avannarleq ENVELOPE(-50.833,-50.833,71.033,71.033) |
institution |
Open Polar |
collection |
University of Arkansas: ScholarWorks@UARK |
op_collection_id |
ftunivarkansas |
language |
unknown |
topic |
Ablation area Arctic Cryosphere Glacial hydrology Glaciology Polar region Climate Geomorphology Hydrology |
spellingShingle |
Ablation area Arctic Cryosphere Glacial hydrology Glaciology Polar region Climate Geomorphology Hydrology Trunz, Celia Modeling and Measuring Water Level Fluctuations in the Greenland Ice Sheet: How Moulin Life Cycle and Shape can Inform us on the Subglacial Drainage System. |
topic_facet |
Ablation area Arctic Cryosphere Glacial hydrology Glaciology Polar region Climate Geomorphology Hydrology |
description |
In the ablation zone of land terminating sectors of the Greenland Ice Sheet (GrIS), water pressures at the bed control ice motion variability on diurnal and seasonal timescales. During the melt season, large volumes of surface meltwater access the ice-bed interface through moulins.Moulins are large vertical shafts that connect the supraglacial and subglacial drainage systems. Moulins form when a crevasse intersects a surface meltwater source that can drive hydrofracture to the bed of the ice sheet. Upon reaching the bed, meltwater can establish and sustain an efficient, channelized drainage system. Due to the technical impossibility of physically exploring underwater passages beneath the GrIS, the subglacial drainage system must be studied through geophysical methods. To date, measurements of water level variability within moulins and boreholes have proved to be critical for constraining models. However, direct hydrologic measurements from the GrIS are sparse, due to the remoteness and harsh conditions of the ice sheet. The work presented in this dissertation combines simple physically based mathematical models with direct measurements from the ablation portion of Sermeq Avannarleq, in west Greenland to advance our understanding of the influence of moulin geometry and life span on glacier dynamics. In Chapter 2, I investigate the moulin life cycle within several neighboring surface catchments within the GrIS ablation zone. A combination of remote sensing and ground observations of moulin locations over two to three years reveals an annual pattern of systematic formation and abandonment of moulins after they are advected down-glacier.In Chapter 3, I use a modified single conduit model to explore the role of moulin shape and size on hydraulic head variability within moulins. This model shows that only the englacial storage capacity within the range of water level fluctuations affects the oscillation range of moulin hydraulic head, which controls subglacial channel water pressure dynamics. Further, the model shows ... |
format |
Text |
author |
Trunz, Celia |
author_facet |
Trunz, Celia |
author_sort |
Trunz, Celia |
title |
Modeling and Measuring Water Level Fluctuations in the Greenland Ice Sheet: How Moulin Life Cycle and Shape can Inform us on the Subglacial Drainage System. |
title_short |
Modeling and Measuring Water Level Fluctuations in the Greenland Ice Sheet: How Moulin Life Cycle and Shape can Inform us on the Subglacial Drainage System. |
title_full |
Modeling and Measuring Water Level Fluctuations in the Greenland Ice Sheet: How Moulin Life Cycle and Shape can Inform us on the Subglacial Drainage System. |
title_fullStr |
Modeling and Measuring Water Level Fluctuations in the Greenland Ice Sheet: How Moulin Life Cycle and Shape can Inform us on the Subglacial Drainage System. |
title_full_unstemmed |
Modeling and Measuring Water Level Fluctuations in the Greenland Ice Sheet: How Moulin Life Cycle and Shape can Inform us on the Subglacial Drainage System. |
title_sort |
modeling and measuring water level fluctuations in the greenland ice sheet: how moulin life cycle and shape can inform us on the subglacial drainage system. |
publisher |
ScholarWorks@UARK |
publishDate |
2021 |
url |
https://scholarworks.uark.edu/etd/4126 https://scholarworks.uark.edu/context/etd/article/5676/viewcontent/Trunz_uark_0011A_14398.pdf |
long_lat |
ENVELOPE(-49.100,-49.100,62.133,62.133) ENVELOPE(-50.833,-50.833,71.033,71.033) |
geographic |
Arctic Avannarleq Greenland Sermeq Avannarleq |
geographic_facet |
Arctic Avannarleq Greenland Sermeq Avannarleq |
genre |
arctic cryosphere Arctic glacier Greenland Ice Sheet |
genre_facet |
arctic cryosphere Arctic glacier Greenland Ice Sheet |
op_source |
Graduate Theses and Dissertations |
op_relation |
https://scholarworks.uark.edu/etd/4126 https://scholarworks.uark.edu/context/etd/article/5676/viewcontent/Trunz_uark_0011A_14398.pdf |
_version_ |
1782329907261472768 |