Intensified extreme cold surges in northern East Asia and the associated changes in atmospheric circulation under climate change
Yongling Dai, Bo Sun, Botao Zhou, Huixin Li, Shengping He, Fei Li, Yue-Tong Huang, Wenchao Tang
Abstract
Despite accelerated global warming, extreme cold surges remain a critical threat to East Asian socio-economic stability. However, research gaps persist regarding trends in the intensity of extreme cold surges over northern East Asia and their physical mechanisms under global warming. Using ERA5 data from 1980 to 2022, this study revealed that while the frequency of extreme cold surges had declined significantly across East Asia (with decreases of 0.64 ( p < 0.1) and 0.94 ( p < 0.01) events per decade in the northern and southern regions, respectively), their intensity had increased dramatically by 0.51 °C per decade ( p < 0.1) in northern East Asia. This enhanced intensity was associated with a strengthened surface Siberian high during extreme cold surges, driven by enhanced Ural pressure ridge and deepened East Asian trough in the mid-troposphere. Furthermore, the warmer Arctic and mid-to-low latitudes during the latter period (2001–2021) weakened the polar front jet while strengthening the subtropical jet stream, facilitating the invasion and accumulation of cold air to northern East Asia. These atmospheric changes further enhanced the Ural pressure ridge and East Asian trough, intensifying the surface Siberian high and ultimately contributing to stronger extreme cold surges in northern East Asia during the latter period. These findings provide new insights into the mechanisms underlying the intensity of extreme cold surges and have implications for long-term forecasting.