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Thursday, July 05, 2012
2:00 PM - 2:45 PM
CNLS Conference Room (TA-3, Bldg 1690)

Postdoc Seminar

Toward modeling ice-sheet/ocean interactions and their consequences for sea-level rise in a global climate model

Xylar Asay-Davis
T-3 and CNLS

Ice sheets are expected to contribute a major fraction of 21st century sea-level rise, partly because of nonlinear feedbacks between climate and ice-sheet dynamics. The rate of ice mass loss is strongly influenced by interactions between the ocean and ice shelves, huge “tongues” of floating ice attached to the ice sheet. Theoretical arguments and numerical simulations indicate that marine ice sheets (those lying on bedrock below sea level) are subject to an instability that can lead to rapid ice retreat when the bedrock slopes downward away from the ocean, as is the case in much of West Antarctica. Accurate representation of the geometry and physics at the ice shelf/ocean interface is critical to capturing these dynamics. We have developed a method for simulating ice-shelf/ocean interaction in LANL’s global ocean model, the Parallel Ocean Program (POP). POP is the ocean component of a global climate model, the Community Earth System model. We show preliminary simulations with the new model using both simplified and relatively realistic ice sheet and ocean configurations and climate forcing. The simulations in simplified configurations are used to validate the model against other ocean models that include ice-sheet interactions; the more realistic simulations begin to capture the complex interactions between atmospheric forcing, sea ice, ocean dynamics and melting and freezing under ice shelves. Although the ice/ocean interface is fixed in time in these simulations, we present work in progress on an algorithm (an immersed boundary method) that will allow the interface to move in time.

Host: Kipton Barros, T-4 and CNLS