Precipitation simulation for Dronning Maud Land using the COSMO Model

Abstract

AbstractA weather episode, characterized by the passage of synoptic disturbances, is investigated for Dronning Maud Land, Antarctica. Due to the sparsity of observations, information about the spatial and temporal distribution of precipitation at high resolution can be gained only by modelling. The simulations presented here are performed with the high-resolution, non-hydrostatic weather forecast COSMO Model with a horizontal mesh size of 7 km. The comparison with observations at four stations shows that the simulation captures the general meteorological conditions well, while a warm bias and a weak daily cycle are found in near-surface temperatures. With regard to precipitation, the timing relates well to the observations; the amount of precipitation, however, is that of an extreme event and possibly overestimated in some regions. The horizontal distribution of precipitation is dominated by topographic effects. The simulations show the general decrease of precipitation toward the interior, as seen in the accumulation climatology, however, the decrease is not monotonous. For example, in the simulations horizontal structures such as precipitation bands of some 100 km width appear on the plateau, which can only be resolved by models with mesh sizes of 10 km or less.