The Surface Mass Balance in a Regional Climate Model of Antarctica

Understanding the Earths climate system and particularly climate variability presents one of the most difficult and urgent challenges in science. The Antarctic plays a crucial role in the global climate system, since it is the principal region of radiative energy deficit and atmospheric cooling. The regional climate model HIRHAM has been used for investigating the climate of Antarctica. In comparison with the observations, the evaluation shows that the simulations with the HIRHAM model capture both the large and regional scale circulation features with generally small bias in the modeled variables. The decadal scale processes were studied based on trend calculations. To better understand the horizontal structure of mean sea level pressure, temperature and net mass balance trends the influence of the Antarctic Oscillation (AAO) on the Antarctic climate was investigated. For detailed investigation of global teleconnection, two positive and one negative periods of AAO phase were chosen. The differences in MSLP and 2m temperature between positive and negative AAO years during the winter months partly explain the surface cooling during the last decades.