Impact of mesoscale ocean currents on sea ice in high-resolution Arctic ice and ocean simulations

A high-resolution sea ice model is designed for simulating the Arctic. The grid resolution is similar to 18 km, and the domain contains the main Arcti c Ocean, Nordic Seas, Canadian Archipelago, and the subpolar North Atlantic . The model is based on a widely used dynamic and thermodynamic model with more efficient numerics. The oceanic forcing is from an Arctic Ocean model with the same horizontal resolution as the ice model and 30 levels, The atm ospheric forcing is from 3-day average 1990-1994 European Centre for Medium -Range Weather Forecasts operational data. Results from the ice model are c ompared against satellite passive-microwave observations and drifting buoys . The model realistically simulates ice tongues and eddies in the Greenland Sea. The mesoscale ocean eddies along the East Greenland Current (EGC) are demonstrated to be responsible for the presence of ice eddies and tongues out of the Greenland Sea ice edge. Large shear and divergence associated wi th the mesoscale ice eddies and strong ice drift, such as the one above the EGG, result in thinner and less compact ice. The mesoscale ocean eddies al ong the Alaskan Chukchi shelf break, the Northwind Ridge, and the Alpha-Men deleyev Ridge are major contributors to mesoscale reduction of ice concentr ation, in addition to atmospheric storms which usually lead to a broad-scal e reduction of ice concentration. The existence of mesoscale ocean eddies g reatly increases nonuniformity of ice motion, which means stronger ice defo rmation and more open water. An eddy-resolving coupled ice-ocean model is h ighly recommended to adequately simulate the small but important percentage of open water in the Arctic pack ice, which can significantly change the h eat fluxes from ocean to atmosphere and affect the global climate.