Simulation of sea ice transport through Fram Strait: Natural variability and sensitivity to forcing

The interannual variability of the sea ice transport through Fram Strait is simulated with a dynamic-thermodynamic sea ice model. Forcing with daily varying wind fields for the 7-year period 1986-1992 causes a high variability of sea ice drift on timescales from days to years. Annual means of simulated ice transport through Fram Strait differ up to a factor of 2. Additional sensitivity studies investigate the response of sea ice transports to variations of the prescribed atmospheric and oceanic forcing. Wind speed, ocean current speed, air temperature, and precipitation rate are systematically varied over a wide rang e. The model predicts an almost linear relation of ice transport with wind speed and ocean current, a strong, nonlinear relation with air temperature, and a rather small sensitivity to changes in precipitation. The results show that the interannual variability of wind forcing causes considerable variations of sea ice export through Fram Strait. The fluxes of fresh water and negative latent heat associated with the sea ice transport can significantly affect the ocean circulation in the Greenland Sea and in the North Atlantic. This shows how variations of the ocean circulation are coupled to the variability of the atmosphere by the mechanism of sea ice advection. To adequately represent these important in the coupled system atmosphere-cryosphere-ocean, both the dynamics and the thermodynamics of sea ice must be included in climate models.