HR: 0800h
AN: C21B-1097    [Abstracts]
TI: The Antarctic Ice Sheet: A Temperature-Dependent Model with Coupled Inland Ice Sheet, Ice Stream and Ice Shelf Flow
AU: Kallen-Brown, J A
EM: jbrown@gi.alaska.edu
AF: Dept. of Mathematical Sciences and Statistics, University of Alaska, Fairbanks, AK 99775-6660 United States
AU: Bueler, E
EM: ffelb@uaf.edu
AF: Dept. of Mathematical Sciences and Statistics, University of Alaska, Fairbanks, AK 99775-6660 United States
AU: * Lingle, C S
EM: clingle@gi.alaska.edu
AF: Geophysical Institute, University of Alaska, Fairbanks, AK 99775-7320 United States
AB: A numerical model of the Antarctic ice sheet has been developed that is quasi-three dimensional, includes coupled inland ice-sheet flow, ice-stream flow, and floating ice-shelf flow, and is time- and temperature-dependent. Inland ice-sheet flow is approximated using the shallow ice approximation with the ice rheology represented by the Goldsby-Kohlstedt (G-K, 2001) constitutive equation. Alternatively, the ice sheet rheology in this flow regime can be represented using Glen's flow law (1955). We show quantitatively that the G-K constitutive equation yields a more accurate simulation of the geometry of the Antarctic ice sheet than Glen's flow law in regions where the ice sheet is frozen to its bed (no basal motion). Ice-stream and ice-shelf flow are approximated by longitudinal stress gradients and strain rates; because of the difficulty of inverting the G-K constitutive equation, the ice rheology in these flow regimes is represented using an inverted form of Glen's flow law with nonlinear stress-dependent viscosity. Ice stream grounding line retreat or advance is modeled using a flotation criterion characterized by a seamless transition from grounded to floating ice. Our model builds on and extends the ice sheet / ice-stream / ice-shelf model of Hulbe and MacAyeal (1999), the ice-shelf model of Rommelaere and Ritz (1996), and the Antarctic ice-sheet model of Ritz et al. (2001). Preliminary results, including verification (see Bueler et al., in press) of the simulation of thermocoupled inland ice-sheet flow by comparison with exact solutions, will be presented. Reference: Bueler, E., C.S. Lingle, J.A. Kallen-Brown, D.N. Covey, and L.N. Bowman, Exact solutions and the verification of numerical models for isothermal ice sheets, J. Glaciology, in press 2005.
DE: 0545 Modeling (4255)
DE: 0720 Glaciers
DE: 0726 Ice sheets
DE: 0728 Ice shelves
DE: 0730 Ice streams
SC: Cryosphere [C]
MN: Fall Meeting 2005