HR: 16:30h
AN: C44A-03    [Abstracts]
TI: Grounding line migration and West-Antarctic ice sheet dynamics
AU: * Pattyn, F
EM: fpattyn@vub.ac.be
AF: Department of Geography (WE-DGGF) Vrije Universiteit Brussel, Pleinlaan 2, Brussels, 1170 Belgium
AU: De Smedt, B
EM: bdesmedt@vub.ac.be
AF: Department of Geography (WE-DGGF) Vrije Universiteit Brussel, Pleinlaan 2, Brussels, 1170 Belgium
AB: It has been suggested that rapid thinning of the West-Antarctic ice sheet is due to increased melting under ice shelves caused by a gradual ocean warming. Payne et al. (2004, GRL) showed that such melting could lead to an acceleration of grounded ice flow. However, the model used in their analysis still lacks the proper treatment of both stress coupling across the grounding line and dynamic grounding line migration. Here, both mechanisms are taken into account with subgrid precision in a 2D flowline model. We analyze the response of a marine ice sheet to different perturbations in both the ice shelf and at the grounding line, and show that stress transmission or longitudinal coupling across the grounding line plays a decisive role herein, as the amplitude of grounding line migration is a function of the width of the transition zone. We demonstrate that thinning of the ice shelf due to bottom melting has a negligible effect on the grounded ice mass, and only perturbations at the grounding line or reduction in buttressing of the ice shelf substantially thins the grounded ice sheet. Marine ice sheets with wide transition zones - such as ice streams - seem highly sensitive to such perturbations, compared to ice sheets with small transition zones, such as an abrupt ice sheet/ice shelf junction. The model is also run with existing glacier geometries of Pine Island Glacier (West Antarctica) and Shirase Glacier (East Antarctica) to identify the impact of the different perturbations.
DE: 0700 CRYOSPHERE (4540)
DE: 0726 Ice sheets
DE: 0728 Ice shelves
DE: 0730 Ice streams
DE: 0798 Modeling
SC: Cryosphere [C]
MN: Fall Meeting 2005