83rd Annual

Monday, 10 February 2003
Simulation of the Antarctic climate using the Arctic Region Climate System Model (ARCSyM) and the AVHRR Polar Pathfinder (APP) data set
Michael J. Pavolonis, CIMSS/Univ. of Wisconsin, Madison, WI; and J. R. Key
The cloud mask, cloud top height and cloud optical thickness from the newly extended AVHRR (Advanced Very High Resolution Radiometer) Polar Pathfinder (APP) data set were incorporated into the Arctic Region Climate System Model (ARCSyM) in order to simulate a more realistic Antarctic climate regime. All model simulations were performed using a grid with a horizontal resolution of 200 km and 23 vertical sigma levels with the greatest vertical resolution being near the surface. The model was initialized and forced at the boundaries with European Center for Medium-Range Weather Forecasts (ECMWF) analyses using a sponge boundary condition. Results indicate that model simulations incorporating the APP cloud data more accurately simulate model fields such as near-surface temperature and mean sea level pressure than the baseline model simulations without the APP data. However, the model results still show a significant warm bias near the surface over much of the Antarctic Plateau relative to the ECMWF analysis and surface observations. This implies that the model has difficulty simulating the cold stable boundary layer that is typically present over much of the Antarctic continent, although model performance does improve when the APP product is used to determine the horizontal and vertical location of clouds.

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