Non-linear feedbacks affecting sea ice deformation in the Regional Arctic System Model (RASM)

We present the latest results of high-resolution sea ice simulations from the fully coupled Regional Arctic System Model (RASM), including explicit melt ponds, form drag and anisotropic sea ice rheology. RASM is a pan-Arctic model composed of the Parallel Ocean Program (POP) and Los Alamos Sea ice Model (CICE5) at ~9km resolution, coupled to the Weather Research and Forecasting Model (WRF) and Variable Infiltration Capacity (VIC) model at 50km resolution using the Community Earth System Model (CESM) coupling framework. Using RASM, we have analyzed coupled feedbacks resulting from different sea ice mechanics formulations. Strong spatial and temporal scaling of sea ice deformation has been observed in the Arctic using the Radarsat Geophysical Processing System and Global Positioning System equipped buoys. Whereas previous results from stand-alone ice-ocean simulations suggest that the established Elastic Viscous Plastic (EVP) rheology is unable to replicate these features, RASM simulates the observed scaling using EVP, with a spatial scaling fractal dimension of around -0.23, as compared to the observed range of -0.18 to -0.20. Using this metric, we extend our analysis to test for spatial scaling in sea ice deformation using a recently revised EVP formulation, as well as the new Elastic Plastic Anistropic rheology in CICE5. Our results suggest that a fundamental source of scaling stems from feedbacks associated with frequent coupling between high resolution ocean and atmospheric models, and this result serves as an example of the broader utility of limited-area, fully coupled models in isolating coupled feedbacks and evaluating them using daily in-situ and satellite measurements.