Antarctic mesoscale modeling with MM5: model enhancements and verification

The Polar Meteorology Group (PMG) of the Byrd Polar Research Center at The Ohio State University has extensively modified the Pennsylvania State University / National Center for Atmospheric Research fifth generation mesoscale model (MM5) for use in the Antarctic. Changes to the model include the addition of a sea ice surface type, that allows for fractional sea ice coverage, improved treatment of heat transfer through the snow surface, modified ice cloud parameterizations, modified cloud / radiation interaction for both longwave and shortwave radiation, and the addition of multiple planetary boundary / surface layer parameterizations appropriate for use in the Antarctic. These changes have occurred over a number of years. The model, with the complete suite of modifications, has been used to simulate the Antarctic climate for an entire year. Results from comparisons of the model climate with observations from automatic weather stations and radiosondes in the Antarctic for the months of January and June 1993 will be presented. It will be shown that the PMG modifications to MM5 significantly improve the forecast climate state of the model.