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An investigation into the mechanisms controlling seasonal speedup events at a High Arctic glacier.

Bingham, Robert G.; Hubbard, Alun L.; Nienow, Peter W.; Sharp, Martin J.. 2008 An investigation into the mechanisms controlling seasonal speedup events at a High Arctic glacier. Journal of Geophysical Research, 113 (F2), F02006. 13, pp. 10.1029/2007JF000832

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Abstract/Summary

Seasonal variations in ice motion have been observed at several polythermal ice masses across the High Arctic, including the Greenland Ice Sheet. However, such variations in ice motion and their possible driving mechanisms are rarely incorporated in models of the response of High Arctic ice masses to predicted climate warming. Here we use a three-dimensional finite difference flow model, constrained by field data, to investigate seasonal variations in the distribution of basal sliding at polythermal John Evans Glacier, Ellesmere Island, Canada. Our results suggest that speedups observed at the surface during the melt season result directly from changes in rates of basal motion. They also suggest that stress gradient coupling is ineffective at transmitting basal motion anomalies to the upper part of the glacier, in contrast to findings from an earlier flow line study at the same glacier. We suggest that stress gradient coupling is limited through the effect of high drag imposed by a partially frozen bed and friction induced by valley walls and significant topographic pinning points. Our findings imply that stress gradient coupling may play a limited role in transmitting supraglacially forced basal motion anomalies through Arctic valley and outlet glaciers with complex topographic settings and highlight the importance of dynamically incorporating basal motion into models predicting the response of the Arctic's land ice to climate change.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1029/2007JF000832
Programmes: BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Glacial Retreat in Antarctica and Deglaciation of the Earth System
ISSN: 0148-0227
Additional Keywords: Arctic, Canada, Ellesmere, glacier dynamics, sea-level, Greenland Ice Sheet, Zwally effect, polythermal, surface melt, basal motion, John Evans Glacier
NORA Subject Terms: Glaciology
Date made live: 30 Jul 2008 15:02
URI: http://nora.nerc.ac.uk/id/eprint/3726

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