Modeling the surface energy budget and the temperature structure of snow and brine-snow at Ice Station Weddell

During the fall of 1992, the four-month drift of Ice Station Weddell (ISW) yielded a wide-ranging set of snow, ice, and meteorological data from the climatologically important western Weddell Sea. We use a detailed, one-dimensional model of snow, SNTHERM, to synthesize these data and to produce energetically consistent time series of all the components of the surface heat budget on ISW. This work incorporates recent adaptations of SNTHERM to a sea ice environment that we developed for predicting the surface energy budget on Russian drifting station North Pole 4. As a test of SNTHERM's ability to model in-snow and boundary layer energy exchange, we compare measured and predicted temperature profiles at 21 levels in the snow and sea ice. SNTHERM closely reproduces in-snow temperatures. It, however, over predicts cooling of the flooded slush layer that commonly occurred at ISW--a feature we did not see in our Arctic studies. Parameterizing the thermal properties of brine-snow improves the predictions. Simulated radiative and turbulent momentum fluxes compare favorably with ISW measurements of those quantities. We also investigate SNTHERM's sensitivity to an hypothesized parameterization for the momentum roughness length, z₀, over sea ice that involves changes in roughness caused by drifting and blowing snow.