Variations of the “warm Arctic-cold Eurasia” pattern and the climate-environment effects

“Warm Arctic-cold Eurasia” (WACE) pattern is one of the key modes of winter Arctic-Eurasia climate variability, existing on multiple time scales. After 2012, the weakening of the “Arctic warming-Eurasia cooling” trend has sparked intense discussions on whether the Arctic-Eurasia climatic linkage has disappeared or weakened. Diagnosis analyses based on multi-source data indicate that the time scale of the close connection between the Arctic and Eurasia climates shifts from the winter-mean to subseasonal variations, presenting the increasing and strengthening phase reversal of WACE between early and late winter. WACE pattern can lead to a weakened large-scale meridional temperature gradient, forming persistent and large-amplitude atmospheric circulation anomalies, thereby triggering the extreme cold waves. More importantly, the WACE reversal can drive the extreme cold-warm transitions in the Mongolian region and eastern China. As Mongolia is a major dust source for China, rapid wintertime phase reversals lead to loose, bare ground surfaces, providing ample material conditions for severe sandstorms in North China.SThe “Warm Arctic-Cold Eurasia” on the subseasonal scale offers a clearer physical features of the variations in early and late winter. The WACE in late winter also significantly impacts the haze pollution in North China and plays a key role in predicting Arctic wildfires. Future research on WACE pattern urgently needs to focus on its trend changes and uncertainties, clarify the trigger mechanism for its phase reversal, and improve the simulation and prediction performance of climate models, in order to enhance the prediction ability for winter-spring extreme climates in mid-low latitudes.