Atmosphere Ocean Science Colloquium
Ice Sheet-Ocean Interactions in the Community Earth System Model (Cesm)
Speaker: Xylar Asay-Davis, NYU/LANL
Location: Warren Weaver Hall 1302
Date: Wednesday, October 23, 2013, 3:30 p.m.
This talk will present our work toward including ice sheet-ocean interactions in a global climate model, the Community Earth System Model (CESM). First, I will focus on my own work in developing a new version of the Los Alamos National Laboratory's Parallel Ocean Program version 2x (POP2x) that includes circulation and thermodynamic interactions in the ocean cavities beneath ice shelves. I will show that POP2x produces basal melt rates that are broadly consistent with observations all around Antarctica. These simulations use present-day climate forcing (the CORE2 Normal Year) and observed, time-independent ice-sheet geometry (Bedmap2). I show that the melt rates are surprisingly insensitive to uncertain parameters associated with the ice-ocean boundary layer under ice shelves (such as the surface roughness, and heat- and salt-transfer coefficients). Second, I will present work in collaboration with the developers of the Community Ice-Sheet Model (CISM) on coupled ice sheet-ocean simulations. To date, our coupled modeling has focused on an idealized model configuration reminiscent of Pine Island Glacier, one of the fastest retreating glaciers in the world, using offline (asynchronously) coupling: Each model runs for a coupling time step based on boundary conditions from the other model's previous time step. Finally, I will show preliminary work toward adding ice sheet-ocean interactions to a next-generation ocean model, the Model for Prediction Across Scales (MPAS) Ocean, also under development at Los Alamos National Laboratory. MPAS Ocean simulations with a simplified ice shelf suggest that the new model's adaptable vertical coordinate and unstructured horizontal grid may make it an ideal candidate for simulations focused on both Greenland and Antarctic ice sheet-ocean interactions.