HR: 0800h
AN: C51B-0397    [Abstracts]
TI: Debris-Rich Basal Ice Layers Effects on Polar Glacier Dynamics
AU: * Whorton, E N
EM: ewclimb@u.washington.edu
AF: University of Washington, Johnson Hall 070 Box 351310, Seattle, WA 98195, United States
AU: Pettit, E C
EM: epettit@pdx.edu
AF: Portland State University, PO Box 751, Portland, OR 97207, United States
AU: Sletten, R S
EM: sletten@ess.washington.edu
AF: University of Washington, Johnson Hall 070 Box 351310, Seattle, WA 98195, United States
AU: Hallet, B
EM: hallet@ess.washington.edu
AF: University of Washington, Johnson Hall 070 Box 351310, Seattle, WA 98195, United States
AB: Deformation in a glacier is concentrated near the bed where shear stresses are highest. Deformation may be enhanced significantly when the basal ice of a glacier consists of debris-rich ice, which is typically weaker than clean ice. We present results from a study exploring (1) the importance of these basal layers to the large-scale flow dynamics in the terminus region of Taylor Glacier, a cold-based outlet glacier of the East Antarctic Ice Sheet and (2) the effects of deformation on the longitudinal variation in the thickness of these layers. We use a two-layer two-dimensional flow-band model to study the relative contributions from the debris-rich basal ice and the overlying clean ice to the deformation rates in the terminus region of Taylor Glacier. Field data, including ground penetrating radar, ablation rate, ice temperature, and surface velocity measurements, allow us to validate model results and determine both the best combination of clean and debris-rich basal ice softness parameters, and the spatial variability of the basal ice thickness. We present theoretical evidence supported by three years of observations that the debris-rich basal ice structure (1) controls the large-scale deformation field in the terminus region of Taylor Glacier and (2) is affected by the deformation field such that the layer varies in thickness along the flow-band. As many polar glaciers and ice sheets have prominent debris-rich basal ice layers that crop out at their margins, and interactions between these weak layers and the overall glacier dynamics are significant, it would be worthwhile to incorporate rheologically distinct layers in models of polar glacier dynamics.
DE: 0720 Glaciers
DE: 0774 Dynamics
SC: Cryosphere [C]
MN: 2007 Fall Meeting