Under the background of global warming, the impact of Arctic sea-ice loss on mid-latitude weather and climate in the Northern Hemisphere has attracted widespread attention. However, the underlying physical mechanisms remain debated. Combining observations and model simulations, we demonstrate that early-winter sea-ice loss in the Barents-Kara Seas (BKS) enhances atmospheric baroclinicity and frontogenesis, leading to increased daily cold extremes over East Asia. This study investigates the influence of BKS sea-ice loss on winter surface air temperatures in China, focusing on both tropospheric and stratosphere-troposphere coupling processes. Furthermore, the respective roles of tropospheric processes and stratosphere-troposphere coupling processes are investigated. For the tropospheric processes, an eastward propagating wave train stimulated by sea-ice loss induces negative geopotential height anomalies over the western Pacific, favorable for the transport of cold airmass into China. In terms of the stratosphere-troposphere coupling processes, sea-ice loss leads to the extension of stratospheric polar vortex edge toward North China by modulating upward propagating planetary waves. These results could improve our understanding of the potential linkage between Arctic sea-ice loss and winter weather extremes in East Asia.
 

Arctic Sea-ice,climate extremes,Mid-latitude atmospheric changes