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The Annual Glaciohydrology Cycle in the Ablation Zone of the Greenland Ice Sheet: Part 1. Hydrology ModelWe apply a novel one-dimensional glacier hydrology model that calculates hydraulic head to the tidewater-terminating Sermeq Avannarleq flowline of the Greenland ice sheet. Within a plausible parameter space, the model achieves a quasi-steady-state annual cycle in which hydraulic head oscillates close to flotation throughout the ablation zone. Flotation is briefly achieved during the summer melt season along a approx.17 km stretch of the approx.50 km of flowline within the ablation zone. Beneath the majority of the flowline, subglacial conduit storage closes (i.e. obtains minimum radius) during the winter and opens (i.e. obtains maximum radius) during the summer. Along certain stretches of the flowline, the model predicts that subglacial conduit storage remains open throughout the year. A calculated mean glacier water residence time of approx.2.2 years implies that significant amounts of water are stored in the glacier throughout the year. We interpret this residence time as being indicative of the timescale over which the glacier hydrologic system is capable of adjusting to external surface meltwater forcings. Based on in situ ice velocity observations, we suggest that the summer speed-up event generally corresponds to conditions of increasing hydraulic head during inefficient subglacial drainage. Conversely, the slowdown during fall generally corresponds to conditions of decreasing hydraulic head during efficient subglacial drainage.
Document ID
20120009100
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Colgan, William (Colorado Univ. Boulder, CO, United States)
Rajaram, Harihar (Colorado Univ. Boulder, CO, United States)
Anderson, Robert (Colorado Univ. Boulder, CO, United States)
Steffen. Konrad (Colorado Univ. Boulder, CO, United States)
Phillips, Thomas (Colorado Univ. Boulder, CO, United States)
Zwally, H. Jay (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Abdalati, Waleed (NASA Headquarters Washington, DC United States)
Date Acquired
August 25, 2013
Publication Date
January 1, 2012
Subject Category
Geophysics
Report/Patent Number
GSFC.JA.6178.2012
Funding Number(s)
CONTRACT_GRANT: NNX07AF15G
CONTRACT_GRANT: NNX08AT85G
Distribution Limits
Public
Copyright
Public Use Permitted.

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