NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Links Between Acceleration, Melting, and Supraglacial Lake Drainage of the Western Greenland Ice SheetThe impact of increasing summer melt on the dynamics and stability of the Greenland Ice Sheet is not fully understood. Mounting evidence suggests seasonal evolution of subglacial drainage mitigates or counteracts the ability of surface runoff to increase basal sliding. Here, we compare subdaily ice velocity and uplift derived from nine Global Positioning System stations in the upper ablation zone in west Greenland to surface melt and supraglacial lake drainage during summer 2007. Starting around day 173, we observe speedups of 6-41% above spring velocity lasting 40 days accompanied by sustained surface uplift at most stations, followed by a late summer slowdown. After initial speedup, we see a spatially uniform velocity response across the ablation zone and strong diurnal velocity variations during periods of melting. Most lake drainages were undetectable in the velocity record, and those that were detected only perturbed velocities for approx 1 day, suggesting preexisting drainage systems could efficiently drain large volumes of water. The dynamic response to melt forcing appears to (1) be driven by changes in subglacial storage of water that is delivered in diurnal and episodic pulses, and (2) decrease over the course of the summer, presumably as the subglacial drainage system evolves to greater efficiency. The relationship between hydrology and ice dynamics observed is similar to that observed on mountain glaciers, suggesting that seasonally large water pressures under the ice sheet largely compensate for the greater ice thickness considered here. Thus, increases in summer melting may not guarantee faster seasonal ice flow.
Document ID
20120015198
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Hoffman, M. J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Catania, G. A.
(Texas Univ. Austin, TX, United States)
Neumann, T. A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Andrews, L. C.
(Texas Univ. Austin, TX, United States)
Rumrill, J. A.
(Southern Connecticut State Coll. New Haven, CT, United States)
Date Acquired
August 26, 2013
Publication Date
December 28, 2011
Publication Information
Publication: Journal of Geophysical Research
Volume: 116
Subject Category
Geophysics
Report/Patent Number
GSFC.JA.7002.2012
Funding Number(s)
CONTRACT_GRANT: NNG06GA83G
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available