Influences of the North Atlantic Oscillation on extreme temperature during the cold period in China

Extreme climate shifts were frequently recognized over the Eurasia land, and the atmospheric anomalies have been widely deemed as one of the potential causes for the shifts. In this study, the North Atlantic Oscillation (NAO) was initially assumed as the primary factor leading to changes in temperature extremes in China during the cold period. Then, influencing modes and mechanisms of the NAO on cold period extreme temperatures were both explored with a time lag estimation and a correlation analysis using a stream function and a zonal index. The results indicated that decadal variations in the NAO were the main cause for changes in wintertime extreme temperatures, especially after the turning point in the late 1990s, when the phase changed from positive to negative and extreme temperatures occurred with a significantly increasing tendency. Rossby waves derived from the west wind near the Mediterranean were also responsible for this phenomenon, and the upstream effect and group winds were potential pathways for Rossby wave train functions. These results could be a reference for influence and mechanism exploration between extreme climate and atmospheric circulation factors and could provide a new way of thinking for similar studies in the future.