Development of an Antarctic regional climate system model. Part I: Sea ice and large-scale circulation

A coupled atmosphere-ice regional model previously used for simulations in the Arctic has been implemented in the Antarctic. Three 14-month simulations were performed for 1988-89, with different oceanic specifications. The year 1988 was interesting as there were several sensible heat polynya events in the Cosmonaut Sea region, the investigation of which is the goal of future finer-resolution simulations. Overall, the regional climate model produces reasonable simulations of the Antarctic at 100-km resolution. Root-mean-square errors range from 4 hPa in surface pressure, 4 K in near-surface air temperature, and 3 m s^-1 in near-surface winds, to 1 K in air temperature and 2 m s^-1 in winds at the 500-hPa level. Tests of the coupled system response to oceanic heat flux suggest that the sea-ice simulation is more sensitive than the atmospheric circulation, but it could be expected that the atmosphere would respond to these changes in sea ice over longer time periods than those of interest here. This sensitivity argues for the need for interactive ocean thermodynamics to successfully simulate Antarctic sea-ice distributions.