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Widespread moulin formation during supraglacial lake drainages in Greenland


Hoffman, Matthew J; Perego, Mauro; Andrews, Lauren C; Price, Stephen F; Neumann, Thomas A; Johnson, Jesse V; Catania, Ginny; Lüthi, Martin P (2018). Widespread moulin formation during supraglacial lake drainages in Greenland. Geophysical Research Letters, 45(2):778-788.

Abstract

Moulins permit access of surface meltwater to the glacier bed, causing basal lubrication and ice speedup in the ablation zone of western Greenland during summer. Despite the substantial impact of moulins on ice dynamics, the conditions under which they form are poorly understood. We assimilate a time series of ice surface velocity from a network of eleven Global Positioning System receivers into an ice sheet model to estimate ice sheet stresses during winter, spring, and summer in a ∼30 × 10 km region. Surface-parallel von Mises stress increases slightly during spring speedup and early summer, sufficient to allow formation of 16% of moulins mapped in the study area. In contrast, 63% of mourns experience stresses over the tensile strength of ice during a short (hours) supraglacial lake drainage event. Lake drainages appear to control moulin density, which is itself a control on subglacial drainage efficiency and summer ice velocities.

Abstract

Moulins permit access of surface meltwater to the glacier bed, causing basal lubrication and ice speedup in the ablation zone of western Greenland during summer. Despite the substantial impact of moulins on ice dynamics, the conditions under which they form are poorly understood. We assimilate a time series of ice surface velocity from a network of eleven Global Positioning System receivers into an ice sheet model to estimate ice sheet stresses during winter, spring, and summer in a ∼30 × 10 km region. Surface-parallel von Mises stress increases slightly during spring speedup and early summer, sufficient to allow formation of 16% of moulins mapped in the study area. In contrast, 63% of mourns experience stresses over the tensile strength of ice during a short (hours) supraglacial lake drainage event. Lake drainages appear to control moulin density, which is itself a control on subglacial drainage efficiency and summer ice velocities.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Geography
Dewey Decimal Classification:910 Geography & travel
Uncontrolled Keywords:General Earth and Planetary Sciences, Geophysics
Language:English
Date:28 January 2018
Deposited On:30 Jan 2019 15:39
Last Modified:30 Jan 2019 15:42
Publisher:American Geophysical Union
ISSN:0094-8276
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1002/2017gl075659
Project Information:
  • : FunderSNSF
  • : Grant ID200021_127197
  • : Project TitleSubglacial Controls on the Short Term Dynamics at the Margin of the Greenland Ice Sheet

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