C51A-0683
Inter-comparison of isotropic and anisotropic sea ice rheology in a fully coupled model
Friday, 18 December 2015
Poster Hall (Moscone South)
Andrew Roberts1, John J Cassano2, Wieslaw Maslowski1, Robert Osinski3, Mark W Seefeldt2, Mimi Hughes2, Alice Duvivier4, Bart Nijssen5, Joseph Hamman5, Jennifer K Hutchings6 and Elizabeth C Hunke7, (1)Naval Postgraduate School, Monterey, CA, United States, (2)University of Colorado at Boulder, Boulder, CO, United States, (3)The Institute of Oceanology Polish Academy of Sciences, Sopot, Poland, (4)CIRES, Boulder, CO, United States, (5)University of Washington, Seattle, WA, United States, (6)Oregon State University, College of Earth, Ocean and Atmospheric Sciences, Corvallis, OR, United States, (7)Los Alamos National Laboratory, T-3 Fluid Dynamics and Solid Mechanics Group, Los Alamos, NM, United States
Abstract:
We present the sea ice climate of the Regional Arctic System Model (RASM), using a suite of new physics available in the Los Alamos Sea Ice Model (CICE5). RASM is a high-resolution fully coupled pan-Arctic model that also includes the Parallel Ocean Program (POP), the Weather Research and Forecasting Model (WRF) and Variable Infiltration Capacity (VIC) land model. The model domain extends from ~45˚N to the North Pole and is configured to run at ~9km resolution for the ice and ocean components, coupled to 50km resolution atmosphere and land models. The baseline sea ice model configuration includes mushy-layer sea ice thermodynamics and level-ice melt ponds. Using this configuration, we compare the use of isotropic and anisotropic sea ice mechanics, and evaluate model performance using these two variants against observations including Arctic buoy drift and deformation, satellite-derived drift and deformation, and sea ice volume estimates from ICESat. We find that the isotropic rheology better approximates spatial patterns of thickness observed across the Arctic, but that both rheologies closely approximate scaling laws observed in the pack using buoys and RGPS data. A fundamental component of both ice mechanics variants, the so called Elastic-Viscous-Plastic (EVP) and Anisotropic-Elastic-Plastic (EAP), is that they are highly sensitive to the timestep used for elastic sub-cycling in an inertial-resolving coupled framework, and this has a significant affect on surface fluxes in the fully coupled framework.
