Extreme spring cold spells in North China during 1961–2014 and the evolving processes

This study presents the major features of extreme spring cold spells (ESCS) in North China during 1961–2014 and the evolving processes. During an ESCS, northern Eurasia is controlled by large-scale positive SLP anomalies and an anomalous anticyclone that continuously transport northern cold air to North China, causing significant, persistent, lower-than-normal daily temperatures. In fact, these positive SLP and anticyclonic wind anomalies begin to appear over northwestern Europe about 10 days prior to the ESCS. The anticyclonic wind anomalies keep moving southeastward and expand to the west of Lake Baikal until two days before the ESCS. Then, the center of the anomalous low-level anticyclone moves over Lake Baikal, inducing northerly wind anomalies that transport cold air into North China. In the following days, as the positive SLP anomalies weaken, the anomalous anticyclone and related northerly winds appear to wane, and the ESCS gradually comes to an end. The results may prove meaningful for the prediction and early warning of ESCSs.