Surface Amplification of Stratospheric Sudden Warming by Poleward Mass Flux in the Upper Troposphere and Lower Stratosphere

Abstract Stratospheric sudden warming (SSW) is the most dramatic event in the winter polar stratosphere, characterized by a rapid temperature increase and a reversal of climatological westerly to easterly. Due to its significant and long-lasting impact on surface climate, SSW and its amplification at the surface have been extensively studied. However, the mechanism underlying the surface impact of SSW remains unclear. In this study, we show that the SSW-induced tropospheric anomaly, which amplifies at the surface, is primarily caused by an increase in Arctic surface pressure. The increase of Arctic surface pressure results from a poleward mass flux across the Arctic Circle, which is determined by the poleward propagation of planetary-scale waves in the upper troposphere and lower stratosphere, in response to the mean flow change in the lowermost stratosphere during the SSW. This result s…