Atmospheric Dynamics and Thermal Asymmetry in the Antarctic Peninsula Region

This paper analyzes the influence that atmospheric circulation in the Antarctic Peninsula region had on thermal conditions on its western (Polish Antarctic Arctowski Station) and eastern (Czech Antarctic Mendel Station) coasts from 2012 to 2024. Based on 850 hPa geopotential height fields from the ERA5 reanalysis, nine anticyclonic and nine cyclonic circulation types were automatically distinguished based on the method proposed by Jenkinson and Collison (1977). Although cyclonic types dominate every month, the contribution of southern advection increases in winter. The frequency of these types varies from year to year and significantly correlates with the large-scale hemispheric process: the Southern Annular Mode (SAM) described by the Antarctic Oscillation index. Advection direction was found to have a significant effect on temperature at both stations. Advection from the west and north causes warming, whereas the inflow of air masses from the south and east causes significant temperature drops. Based on analysis of temperature differences between the Arctowski and Mendel stations, the western coast of the Antarctic Peninsula is significantly warmer than the eastern coast. The studied circulation patterns suggested that the differences between Arctowski and Mendel stations are largest with advection from the south and smaller with zonal advection from the west. Changes in the frequency of atmospheric types in individual years significantly influence air temperature variation. In the warmest years, the frequency of types with advection from the west and north is greater, whereas meridional circulation from the south causes significant cooling.