HR: 13:40h
AN: C53A-01 INVITED    [Abstracts]
TI: Seasonal Ice Acceleration Near the Greenland Ice Sheet Margin
AU: * Neumann, T A
EM: thomas.neumann@uvm.edu
AF: Geology Department, 180 Colchester Ave. University of Vermont, Burlington, VT 05405, United States
AU: Catania, G
EM: gcatania@utig.ig.utexas.edu
AF: Institute for Geophysics Jackson School of Geosciences, 10100 Burnet Road (R2200) University of Texas - Austin, Austin, TX 78758-4445, United States
AU: Rumrill, J
EM: JRumrill@uvm.edu
AF: Geology Department, 180 Colchester Ave. University of Vermont, Burlington, VT 05405, United States
AB: Seasonal changes in ice velocity, depending upon their extent both spatially and temporally, may be important considerations when assessing the stability of inland glacier ice. Work by Zwally and others (2002) suggested potential ice sheet instability in Greenland due to the penetration of summer melt water from the surface of the ice sheet to the bed, where it promotes basal motion. The implication is that this process could lead to rapid disintegration of the Greenland ice sheet as surface melt becomes more common in a warming climate. The recent IPCC 4th Assessment Report points out that such dynamic responses are currently not used in projections of sea level rise; consequently, current estimates of future sea level rise may be too low. We present recent field data collected from the vicinity of Swiss Camp, a site near the equilibrium line on the west coast of Greenland. These data show short duration, episodic changes in velocity in both ablation and accumulation areas. The accelerations are synchronous over the scale of a few kilometers, but are not correlated over larger areas. The duration of these events are significantly shorter than those reported by Zwally et al. (2002), lasting at most two weeks; most are shorter. Events are consistent with localized, periodic melt water input to the basal water system. We explore the implications of these observations in terms of the subglacial hydrologic system near the ice sheet margin and ice sheet stability in a warming climate.
DE: 0726 Ice sheets
DE: 0738 Ice (1863)
DE: 0774 Dynamics
DE: 0776 Glaciology (1621, 1827, 1863)
SC: Cryosphere [C]
MN: 2007 Fall Meeting