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Seasonal evolution of the subglacial hydrologic system modified by supraglacial lake drainage in western Greenland


Andrews, Lauren C; Hoffman, Matthew J; Neumann, Thomas A; Catania, Ginny A; Lüthi, Martin P; Hawley, Robert L; Schild, Kristin M; Ryser, Claudia; Morriss, Blaine F (2018). Seasonal evolution of the subglacial hydrologic system modified by supraglacial lake drainage in western Greenland. Journal of Geophysical Research: Earth Surface, 123(6):1479-1496.

Abstract

The impact of summer surface melt on Greenland Ice Sheet dynamics is modulated by the state of the subglacial hydrologic system. Studies of ice motion indicate that efficiency of the subglacial system increases over the melt season, decreasing the sensitivity of ice motion to surface melt inputs. However, the behavior of the subglacial hydrologic system is complex and some characteristics are still poorly constrained. Here we investigate the coevolution of subglacial hydrology and ice motion in the Pâkitsoq region of western Greenland during the 2011 melt season. We analyze measurements from 11 Global Positioning System stations, from which we derive ice velocity, longitudinal strain rates, and basal uplift, alongside observations of surface ablation and supraglacial lake drainages. We observe ice acceleration after the onset of local surface melting, followed by gradual ice deceleration, consistent with increasing subglacial efficiency. In the study area, supraglacial lake drainages cooccur with a change in regional strain rate patterns and ice deceleration, suggesting that lake drainages contribute to rapid subglacial reorganization. At lower ice surface elevations (below ~900 m above sea level), ice motion is correlated with both total basal uplift and its rate of change, while at higher elevations (~900–1,100 m above sea level), ice motion correlated only with the basal uplift rate. This pattern suggests that continued cavity growth or subglacial sediment dynamics may be important in the apparent increase in subglacial drainage efficiency at higher elevations in the ablation zone. Our results further suggest that transient subglacial behavior is important in the seasonal evolution of ice motion.

Abstract

The impact of summer surface melt on Greenland Ice Sheet dynamics is modulated by the state of the subglacial hydrologic system. Studies of ice motion indicate that efficiency of the subglacial system increases over the melt season, decreasing the sensitivity of ice motion to surface melt inputs. However, the behavior of the subglacial hydrologic system is complex and some characteristics are still poorly constrained. Here we investigate the coevolution of subglacial hydrology and ice motion in the Pâkitsoq region of western Greenland during the 2011 melt season. We analyze measurements from 11 Global Positioning System stations, from which we derive ice velocity, longitudinal strain rates, and basal uplift, alongside observations of surface ablation and supraglacial lake drainages. We observe ice acceleration after the onset of local surface melting, followed by gradual ice deceleration, consistent with increasing subglacial efficiency. In the study area, supraglacial lake drainages cooccur with a change in regional strain rate patterns and ice deceleration, suggesting that lake drainages contribute to rapid subglacial reorganization. At lower ice surface elevations (below ~900 m above sea level), ice motion is correlated with both total basal uplift and its rate of change, while at higher elevations (~900–1,100 m above sea level), ice motion correlated only with the basal uplift rate. This pattern suggests that continued cavity growth or subglacial sediment dynamics may be important in the apparent increase in subglacial drainage efficiency at higher elevations in the ablation zone. Our results further suggest that transient subglacial behavior is important in the seasonal evolution of ice motion.

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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
Scopus Subject Areas:Physical Sciences > Geophysics
Life Sciences > Forestry
Physical Sciences > Oceanography
Life Sciences > Aquatic Science
Physical Sciences > Ecology
Physical Sciences > Water Science and Technology
Life Sciences > Soil Science
Physical Sciences > Geochemistry and Petrology
Physical Sciences > Earth-Surface Processes
Physical Sciences > Atmospheric Science
Physical Sciences > Earth and Planetary Sciences (miscellaneous)
Physical Sciences > Space and Planetary Science
Physical Sciences > Paleontology
Language:English
Date:1 June 2018
Deposited On:30 Jan 2019 15:00
Last Modified:29 Jul 2020 09:28
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:2169-9003
OA Status:Hybrid
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1029/2017jf004585
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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