On February 6, 2020, the Argentinian Esperanza Base on the Antarctic Peninsula recorded a record-high temperature of 18.3 °C. This study investigates the atmospheric circulation responsible for this event using weather observations since 1973 and ERA5 reanalysis data. A high-pressure ridge and a blocking high over the Drake Passage resulted in an anticyclonic circulation, transporting warm, moist air from the Pacific Ocean to the Antarctic Peninsula. Vertical air flows in a foehn warming event, dominated by sensible heat and radiation, were the primary contributor to the abrupt warming. Analysis of 196 extreme warm events between 1973 and 2020 shows that the mechanisms behind the 2020 event are among the two most common clusters, indicating that most extreme warm events at Esperanza are linked to Pacific air masses.

Min Xu, Lejiang Yu, Kaixin Liang, Timo Vihma, Deniz Bozkurt, Xiaoming Hu, Qinghua Yang