Modelling and parameterization of lead generated turbulence in the atmospheric boundary layer of Arctic sea ice
Leads are channel-like openings in the sea ice with a width of some meters up to several kilometers and a length of up to several hundred kilometers. They are caused by divergence or shear in the sea ice drift, caused by wind and ocean currents. Although leads in the polar regions only contribute a few percent to the total ice coverage, they play an important role in the energy balance. Thus, the net heat flux from the ocean to the atmosphere in polar regions is significantly increased by these openings in the ice. Measurements in winter, for example, have shown a contribution of up to 70% for the western Weddelsea. Directly above the leads heat fluxes of a few hundred watts per square meter typically occur.
Since leads are not resolved by weather and climate models, the influences on the energy balance are indirectly taken into account via parameterizations. In this project, using the turbulence-resolving model PALM, the flow over leads is to be explicitly simulated for different cases. Here, a deeper understanding of the exchange processes between ocean and atmosphere through leads is to be obtained, with which in cooperation with the Alfred Wegener Institute Bremerhaven appropriate parameterization should be improved.