HR: 14:55h
AN: C43A-06    [Abstracts]
TI: Investigation of the Velocity Field and Flow Regime of David Glacier and Drygalski Ice Tongue, Antarctica
AU: * Wuite, J
EM: wuite.1@osu.edu
AF: Byrd Polar Research Center, 1090 Carmack Road, Columbus, OH 43210 United States
AU: Jezek, K C
EM: jezek.1@osu.edu
AF: Byrd Polar Research Center, 1090 Carmack Road, Columbus, OH 43210 United States
AB: Recent observations of outlet glaciers in both Greenland and Antarctica show surprising and unexpectedly rapid changes in flow velocities. Outlet glaciers drain the majority of the polar ice sheets and consequently these changes threaten their stability and can lead to rising sea levels. It is therefore important to investigate their flow governing processes and document changes. We measured surface velocity over large portions of David Glacier and its floating seaward extension Drygalski Ice Tongue. This is the largest outlet glacier on the Scott Coast draining a section of the East Antarctic Ice Sheet into the Ross Sea. Giant iceberg B15-A recently collided with the ice tongue and broke off a significant section. To obtain velocities we used combinations of intensity feature tracking, interferometric speckle tracking and phase interferometry using RADARSAT-1 images acquired during the AMM-1 and MAMM missions. We compare short term velocities, 3-year averaged velocities and earlier studies to analyze spatial and temporal variability of the surface velocity field. We use obtained velocities, in combination with isostatically derived ice thickness from ICESat data, to estimate basal melting along the glacier. Also we investigate the role of lateral drag through force-budget theory and determine the equilibrium profile of the ice tongue. Unlike for example the West Antarctic Ice Streams and Jakobshavn Isbr‘, our data suggests that the David Glacier velocity field has remained relatively constant from about 1991 - 2000 and likely much longer. The pattern of melting and freezing along the base of the glacier is consistent with an ice pump mechanism. In the fjord lateral drag opposes approximately 90% of the driving stress; this gradually drops to the point where most resistance comes from longitudinal stress gradients. We find the modeled and ICESat derived profile agree favorably suggesting steady state conditions
DE: 0720 Glaciers
DE: 0758 Remote sensing
DE: 0776 Glaciology (1621, 1827, 1863)
DE: 4540 Ice mechanics and air/sea/ice exchange processes (0700, 0750, 0752, 0754)
SC: Cryosphere [C]
MN: Fall Meeting 2005