HR: 0800h
AN: PP51C-0606    [Abstracts]
TI: A Coupled Ice-sheet/Ice-shelf/Sediment Model Applied to Antarctica: Forced and Unforced Variations.
AU: * Pollard, D
EM: pollard@essc.psu.edu
AF: Pennsylvania State University, Earth System Science Center 2217 Earth-Engineering Sci.Bldg., University Park, PA 16802 United States
AU: DeConto, R M
EM: deconto@geo.umass.edu
AF: University of Massachusetts, Department of Geosciences 233 Morrill Science Center, Amherst, MA 01003 United States
AB: A standard large-scale ice-sheet model is extended by (i) adding ice-shelf flow using a new method of combining the scaled equations for sheet and shelf flow, and (ii) coupling with a deforming sediment model that predicts bulk sediment thickness. The combination of sheet and shelf flow equations is heuristic, but allows both horizontal shear and longitudinal stretching without a priori assumptions about the flow regime, and the grounding line is free to migrate. The sediment model includes bulk transport under ice assuming a weakly non-linear till rheology, generation of till by glacial erosion, and ice-free river transport. The combined model explicitly simulates off-shore sediment strata, enabling direct comparisons with the extensively studied Cenozoic glacimarine sediment record on Antarctic continental shelves. Preliminary applications are presented in 1-D flowline simulations, in which surface ice mass balance is prescribed simply to produce 100 ka to 1 Ma scale advances and retreats of coastal ice. Each simulation is run for 10 million years, and the various patterns of offshore sediment strata built up over the course of each run are examined as external conditions are changed (bed profile, pelagic deposition, etc). In other simulations with constant surface mass balance, unforced irregular oscillations of the ice/sediment/bed system occur on ~million year time scales, which, if borne out in larger-scale 3-D experiments, could have played a role in some of the fluctuations observed in Cenozoic δ¹⁸O records.
DE: 0726 Ice sheets
DE: 0728 Ice shelves
DE: 0798 Modeling
DE: 1862 Sediment transport (4558)
DE: 9310 Antarctica (4207)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005