C51B-0710
Moulin distribution and formation on the southwest Greenland ice sheet
Friday, 18 December 2015
Poster Hall (Moscone South)
Vena W. Chu1, Laurence C Smith2, Colin J Gleason2, Kang Yang2, Kristin Poinar3, Ian Joughin4 and Lincoln H Pitcher2, (1)University of California Berkeley, Berkeley, CA, United States, (2)University of California Los Angeles, Los Angeles, CA, United States, (3)Applied Physics Laboratory University of Washington, Kenmore, WA, United States, (4)Univ Washington, Seattle, WA, United States
Abstract:
River moulins represent a significant connection between surface meltwater generated on the Greenland ice sheet and subglacial drainage networks, where increased meltwater can enhance ice sliding dynamics. In this study, a new high-resolution moulin map is created from WorldView-1/2 imagery acquired during the 2012 record melt year for a 12,500 km2 area near Russell Glacier in southwest Greenland. A total of 1,236 moulins are mapped and categorized as being located: in crevasse fields, along a single ice fracture, within drained lake basins, or having no visible formation mechanism. We find the presence of moulins up to 1787 m elevation, with 11% of moulins found above 1600 m elevation: higher than previously mapped moulins and where glaciological theory suggests few moulins should form. Our study observes moulins in both extensional and compressional ice flow regimes (28% of moulins are found in areas of high extensional strain rate >0.005 yr-1), suggesting that strain rates are not a strong indicator of the likelihood for moulin formation. Overall, moulin density tends to increase with higher bed elevation, thinner ice, lower surface slope, higher velocity, and higher strain rate. In sum, moulins are most common in crevassed, thinner ice near the ice sheet edge, but significant quantities also develop at high elevations. This indicates that future inland expansion of melting may create hydrologic connections between the surface and the bed at higher elevations than previously thought.
