A simple parameterization for snowdrift sublimation over Antarctic snow surfaces

The surface heat budget at two sites in the escarpment region of Dronning Maud Land, Antarctica, is evaluated using a surface energy balance model that is applied to meteorological data gathered in austral summer 1997-1998. Vertical profile observations indicate that the effective roughness lengths of momentum, and especially heat and moisture, increase with wind speed. This can be attributed to snowdrift, which in turn affects the budgets of heat and moisture through sublimation of airborne particles. The snowdrift-induced increases in effective roughness lengths are parameterized in terms of friction velocity, which are used in the model to estimate the total latent heat flux and the contributions of the surface and snowdrift components of sublimation. Snowdrift sublimation increases strongly with wind speed and compares fairly well with results from a more sophisticated method to estimate snowdrift sublimation. Calculations show that snowdrift sublimation is as large as surface sublimation at one site and significantly larger at the other colder and more windy site. The parameterization may be used in atmospheric models to evaluate more accurately total sublimation rates.