Amundsen Sea ocean, sea ice, and thermodynamic ice shelf simulation with optimized model parameters

Yoshihiro Nakayama, University of California Irvine - UCI, Earth System Science, Irvine, CA, United States, Eric J Rignot, University of California Irvine, Irvine, CA, United States, Dimitris Menemenlis, Jet Propulsion Laboratory, Pasadena, CA, United States and Michael Schodlok, University of California Los Angeles, Los Angeles, CA, United States
Abstract:
The ice shelves and glaciers of the West Antarctic Ice Sheet are thinning rapidly in the Amundsen Sea. The high basal melt rate of these ice shelves is caused by warm Circumpolar Deep Water (CDW) that mainly intrudes via submarine glacial troughs located at the continental shelf break. Although there have been many studies focusing on the evolution of Pine Island Glacier (PIG), it remains difficult to simulate its future evolution. One of the difficulties stems from the sensitivity of PIG basal melt to oceanic, sea-ice, and atmospheric conditions. For example, a previous study shows that PIG melting is highly sensitive to the depth of thermocline at the Pine Island Ice Shelf front and basal melting of PIG decreased by 50% during summer 2012, which may potentially impact the evolution PIG. In this study, we use state estimation to constrain a regional Amundsen Sea configuration of the Massachusetts Institute of Technology general circulation model (MITgcm) with available observations. The regional MITgcm configuration includes dynamic/thermodynamic sea ice and static thermodynamic ice shelf representation. We fit the model to the available observations by adjusting initial conditions, open boundary conditions, and a few key internal model parameters. This is a first step towards more quantitative understanding of observed PIG evolution and sensitivity studies.
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