A Physical Model of Moulin Formation and Evolution
Nearly all proglacial water discharge from the present-day Greenland Ice Sheet is routed englacially via moulins. Identification of these moulins in high-resolution imagery is a frequent topic of study, but the processes controlling how and where moulins form, including on past ice sheets for which...
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ftnasantrs:oai:casi.ntrs.nasa.gov:20190025205 2023-05-15T16:30:12+02:00 A Physical Model of Moulin Formation and Evolution Andrews, Lauren C. Poinar, Kristin Unclassified, Unlimited, Publicly available May 12, 2019 application/pdf http://hdl.handle.net/2060/20190025205 unknown Document ID: 20190025205 http://hdl.handle.net/2060/20190025205 Copyright, Use by or on behalf of the U.S. Government permitted CASI Geophysics GSFC-E-DAA-TN68842 International Glaciological Society Symposium on Glacial Erosion and Sedimentation; 12-17 May 2019; Madison, WI; United States 2019 ftnasantrs 2019-07-20T23:01:21Z Nearly all proglacial water discharge from the present-day Greenland Ice Sheet is routed englacially via moulins. Identification of these moulins in high-resolution imagery is a frequent topic of study, but the processes controlling how and where moulins form, including on past ice sheets for which remote-sensing data are not available, remain poorly understood. Because moulins may reasonably compose approximately 10-15% of the englacial-subglacial hydrologic system, the evolution and shape of moulins can alter the timing of meltwater inputs to the bed. This evolution can impact both the form of the subglacial hydrologic system and the structure of associated geomorphological structures. Here, we develop a physical model of moulin formation and evolution to constrain the role of englacial processes in controlling the form and structure of the subglacial hydrologic system. Ice deformation within and around a moulin is both viscous and elastic, with the rate of turbulent and heat dissipation from water circulation in the moulin controlling both moulin wall melting and warming of the surrounding ice. We find moulin geometry is responsive to changes in these parameters over hours to days, indicating that diurnal and multi-day variations in surface melt can substantially alter the geometry of a moulin and the pressure-discharge relationship at the bed of the ice sheet. These results should be considered carefully when determining surface water inputs for subglacial hydrologic models. In the future, a parameter space study of these results will be combined with an analytic model to create a predictive, stochastic model of moulin and crevasse locations. This future model will be applicable to constraining the potential for surface-to-bed connections in regions where the exact ice-sheet surface morphology is not known, including ice sheets under future warming atmospheric conditions, and paleo ice sheets, where moulins created modern landforms. Other/Unknown Material Greenland Ice Sheet NASA Technical Reports Server (NTRS) Greenland |
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Open Polar |
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NASA Technical Reports Server (NTRS) |
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ftnasantrs |
language |
unknown |
topic |
Geophysics |
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Geophysics Andrews, Lauren C. Poinar, Kristin A Physical Model of Moulin Formation and Evolution |
topic_facet |
Geophysics |
description |
Nearly all proglacial water discharge from the present-day Greenland Ice Sheet is routed englacially via moulins. Identification of these moulins in high-resolution imagery is a frequent topic of study, but the processes controlling how and where moulins form, including on past ice sheets for which remote-sensing data are not available, remain poorly understood. Because moulins may reasonably compose approximately 10-15% of the englacial-subglacial hydrologic system, the evolution and shape of moulins can alter the timing of meltwater inputs to the bed. This evolution can impact both the form of the subglacial hydrologic system and the structure of associated geomorphological structures. Here, we develop a physical model of moulin formation and evolution to constrain the role of englacial processes in controlling the form and structure of the subglacial hydrologic system. Ice deformation within and around a moulin is both viscous and elastic, with the rate of turbulent and heat dissipation from water circulation in the moulin controlling both moulin wall melting and warming of the surrounding ice. We find moulin geometry is responsive to changes in these parameters over hours to days, indicating that diurnal and multi-day variations in surface melt can substantially alter the geometry of a moulin and the pressure-discharge relationship at the bed of the ice sheet. These results should be considered carefully when determining surface water inputs for subglacial hydrologic models. In the future, a parameter space study of these results will be combined with an analytic model to create a predictive, stochastic model of moulin and crevasse locations. This future model will be applicable to constraining the potential for surface-to-bed connections in regions where the exact ice-sheet surface morphology is not known, including ice sheets under future warming atmospheric conditions, and paleo ice sheets, where moulins created modern landforms. |
format |
Other/Unknown Material |
author |
Andrews, Lauren C. Poinar, Kristin |
author_facet |
Andrews, Lauren C. Poinar, Kristin |
author_sort |
Andrews, Lauren C. |
title |
A Physical Model of Moulin Formation and Evolution |
title_short |
A Physical Model of Moulin Formation and Evolution |
title_full |
A Physical Model of Moulin Formation and Evolution |
title_fullStr |
A Physical Model of Moulin Formation and Evolution |
title_full_unstemmed |
A Physical Model of Moulin Formation and Evolution |
title_sort |
physical model of moulin formation and evolution |
publishDate |
2019 |
url |
http://hdl.handle.net/2060/20190025205 |
op_coverage |
Unclassified, Unlimited, Publicly available |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Ice Sheet |
genre_facet |
Greenland Ice Sheet |
op_source |
CASI |
op_relation |
Document ID: 20190025205 http://hdl.handle.net/2060/20190025205 |
op_rights |
Copyright, Use by or on behalf of the U.S. Government permitted |
_version_ |
1766019912476655616 |