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Title: Seasonal Evolution of the Subglacial Hydrologic System Modified by Supraglacial Lake Drainage in Western Greenland

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),more » 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. Furthermore, our results further suggest that transient subglacial behavior is important in the seasonal evolution of ice motion.« less

Authors:
ORCiD logo [1]; ORCiD logo [2];  [1]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [5]; ORCiD logo [6];  [7];  [8]
  1. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Univ. of Texas, Austin, TX (United States)
  4. Univ. of Zurich, Hanover, NH (United States)
  5. Dartmouth College, Zurich (Switzerland)
  6. Dartmouth College, Zurich (Switzerland); Univ. of Oregon, Eugene, OR (United States)
  7. Swiss Federal Institute of Technology (ETH), Zurich (Switzerland)
  8. Cold Regions Research and Engineering Lab., Hanover, NH (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
1482953
Report Number(s):
LA-UR-18-27505
Journal ID: ISSN 2169-9003
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Earth Surface
Additional Journal Information:
Journal Volume: 123; Journal Issue: 6; Journal ID: ISSN 2169-9003
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Earth Sciences; Greenland Ice Sheet; glacial hydrology; ice motion; ice sheet dynamics

Citation Formats

Andrews, Lauren C., Hoffman, Matthew J., Neumann, Thomas A., Catania, Ginny A., Lüthi, Martin P., Hawley, Robert L., Schild, Kristin M., Ryser, Claudia, and Morriss, Blaine F. Seasonal Evolution of the Subglacial Hydrologic System Modified by Supraglacial Lake Drainage in Western Greenland. United States: N. p., 2018. Web. doi:10.1029/2017JF004585.
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. Seasonal Evolution of the Subglacial Hydrologic System Modified by Supraglacial Lake Drainage in Western Greenland. United States. doi:10.1029/2017JF004585.
Andrews, Lauren C., Hoffman, Matthew J., Neumann, Thomas A., Catania, Ginny A., Lüthi, Martin P., Hawley, Robert L., Schild, Kristin M., Ryser, Claudia, and Morriss, Blaine F. Thu . "Seasonal Evolution of the Subglacial Hydrologic System Modified by Supraglacial Lake Drainage in Western Greenland". United States. doi:10.1029/2017JF004585. https://www.osti.gov/servlets/purl/1482953.
@article{osti_1482953,
title = {Seasonal Evolution of the Subglacial Hydrologic System Modified by Supraglacial Lake Drainage in Western Greenland},
author = {Andrews, Lauren C. and Hoffman, Matthew J. and Neumann, Thomas A. and Catania, Ginny A. and Lüthi, Martin P. and Hawley, Robert L. and Schild, Kristin M. and Ryser, Claudia and Morriss, Blaine F.},
abstractNote = {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. Furthermore, our results further suggest that transient subglacial behavior is important in the seasonal evolution of ice motion.},
doi = {10.1029/2017JF004585},
journal = {Journal of Geophysical Research. Earth Surface},
number = 6,
volume = 123,
place = {United States},
year = {2018},
month = {5}
}

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