Verification of Polar MM5 Simulations of Antarctic Atmospheric Circulation

Verification of a complete annual cycle of 72h nonhydrostatic mesoscale model simulations of the Antarctic atmospheric circulation is presented. The simulations are generated with the Pennsylvania State University-National Center for Atmospheric Research Fifth-generation Mesoscale Model (MM5), which is modified for polar applications, and is referred to as the Polar MM5. With a horizontal resolution of 60km, the Polar MM5 has been run for the period of January 1993 through December 1993 in a yearlong series of short-term forecasts from initial and boundary conditions provided by the operational analyses of the European Centre for Medium-Range Weather Forecasts (ECMWF). For every short-term forecast the model is integrated for 72 hours with the first 24 hours being discarded for spin-up purposes. The simulations to be analyzed are compiled from the series of remaining 48 hours forecasts. The year 1993 was selected because it was close to average climatological conditions. The model output is verified with observations from automatic weather stations, upper air data, global atmospheric analyses as well as climatological maps over time scales from diurnal to annual. Both the observed atmospheric state over the Antarctic continent and around the coast are reproduced with a high degree of realism. The impact of drift snow redistribution on snow accumulation is also assessed with the simulated surface wind fields.