Near-surface climate of the Antarctic Peninsula as simulated by a high-resolution regional atmospheric climate model

Abstract:

The latest polar version of the regional atmospheric climate model RACMO2 (RACMO2.3) has been applied to the Antarctic Peninsula. Recently, the model physics have been updated, which resulted in a significant improvement in its performance, at 27 km resolution, over East and West Antarctica, in terms of surface energy fluxes and surface mass budget. Here we present results from a climatological run at 5.5 km over the AP for the period 1979-2013, in which RACMO2.3 is forced by ERA-Interim atmospheric and ocean surface fields and includes an AP surface topography based on state of the art digital elevation models.

RACMO2.3 resolves the extremely large gradients over the Antarctic Peninsula mountain spine, in terms of surface and 2 meter temperature, which are caused by the persistent atmospheric westerly winds. We evaluate the model results by comparing them to temperature series from manned and automatic weather stations, vertical profiles from balloon soundings and surface energy balance measurements from three automatic weather stations. Results show that RACMO2.3 performs well in terms of surface and 2 m temperatures, 10 m wind speed/direction, but we also identify some significant biases in the downwelling fluxes of shortwave- and longwave radiation, related to clouds. These biases largely compensate each other, however, so that melt energy fluxes are resolved with reasonable accuracy.