Evaluation of temperature and wind over Antarctica in a Regional Atmospheric Climate Model using 1 year of automatic weather station data and upper air observations

The Regional Atmospheric Climate Model version 2 (RACM02/ANT) is used to simulate the Antarctic atmosphere for the year 1998. The parameterizations of the physical processes in the model are taken from the European Centre for Medium-Range Weather Forecasts (ECMWF) global model and adapted to better represent the specific conditions over the Antarctic continent. The snow albedo was increased by decreasing the rate of albedo change as a function of temperature. This results in a decrease, and an improvement, in near-surface air temperatures in summer, especially over the Antarctic plateau. The surface roughness length for momentum was decreased. This increases the wind speed over the total atmospheric column. As a result, wind speeds better correspond to measurements, especially near the surface and in high wind speed areas. Comparison with ECMWF 40-year reanalyses (ERA40) data show that RACM02/ANT better reproduces the near-surface conditions in terms of temperature and wind speed mainly due to the changes made to the physics description. Away from the surface, ERA40 better corresponds to observations due to the inclusion of the observed profiles in the reanalyses.