HR: 11:05h
AN: C21D-04    [PDF]
TI: Siple Dome: a Case Study of Flow Near an Ice Divide
AU: * Pettit, E C
EM: epettit@ess.washington.edu
AF: University of Washington Department of Earth and Space Sciences, Campus Box 351310, Seattle, WA 98195 United States
AU: Waddington, E D
EM: edw@ess.washington.edu
AF: University of Washington Department of Earth and Space Sciences, Campus Box 351310, Seattle, WA 98195 United States
AU: Jacobson, H P
EM: paul@ess.washington.edu
AF: University of Washington Department of Earth and Space Sciences, Campus Box 351310, Seattle, WA 98195 United States
AU: Zumberge, M A
EM: zumberge@ucsd.edu
AF: Scripts Institute of Oceanography, University of California, San Diego, La Jolla, CA 92093 United States
AU: Husmann, E
AF: Scripts Institute of Oceanography, University of California, San Diego, La Jolla, CA 92093 United States
AU: Harrison, W D
EM: harrison@gi.alaska.edu
AF: Geophysical Institute, University of Alaska, Fairbanks, Fairbanks, AK 99775-7320 United States
AU: Elsberg, D H
EM: ftdhe@uaf.edu
AF: Geophysical Institute, University of Alaska, Fairbanks, Fairbanks, AK 99775-7320 United States
AU: Morack, J L
EM: ffjlm@aurora.alaska.edu
AF: Geophysical Institute, University of Alaska, Fairbanks, Fairbanks, AK 99775-7320 United States
AU: Thorsteinsson, T
EM: throsturt@raunvis.hi.is
AF: Science Institute University of Iceland, Hofsvallagotu 53, Haga, Reykjavik, 107 Iceland
AU: Lamorey, G
EM: gregg.lamorey@dri.edu
AF: Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512 United States
AB: Siple Dome, West Antarctica, is the site of a recent deep ice core. Its dynamic behavior has been inferred through surface strain networks, ice-penetrating radar, and {\it in situ} strain gauge arrays. In this case study, we explore the combined effects of crystal anisotropy, temperature, and rheology on the unique dynamic behavior of steady-state ice divides. The low-stress regime near ice divides causes a flow anomaly due to the non-linearity of ice flow. This phenomenon is observable as an arch in the internal layer structure (imaged by radar). The pattern of divide flow can be inverted for flow law parameters. Specifically, at low stresses, the dominant micro-scale flow mechanism shifts to one that is more linear. This shift is expressed as a change in the flow-law exponent; therefore its effect is distinguishable from that of anisotropy or temperature. We have developed a 2D plane-strain finite-element flow model with a two-term flow law modified for anisotropic flow. With this model and available measurements, we use Siple Dome as a case study to assess the relative importance of linear-viscous behavior compared to anisotropic behavior and discuss the implications for other ice divides.
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2003 Fall Meeting