Abstract
Through both observational analyses and simulation experiments, this study investigates the intraseasonal evolution of atmospheric circulation anomalies associated with a persistent cold event in the Asian continent during late January–early February 2012, and the possible association with Arctic sea ice loss and Arctic atmospheric circulation during the preceding summer. The results suggest that the northeastern Pacific–Aleutian region and central Eurasia are two critical areas where the atmospheric circulation evolution contributed to the development of this cold event. A persistent increase in sea level pressure (SLP) over the Aleutian region was a predominant feature prior to the cold event, and then decreasing SLP over this region was concurrent with both occurrence of a polar blocking high aloft and rapid strengthening of the Siberian high, triggering outbreaks of Arctic air over the Asian continent. Consequently, the influence of the Aleutian region on this cold event (i.e., the downstream effect of the atmospheric circulation) played a critical role. Simulation experiments demonstrate that Arctic atmospheric circulation conditions in the summer of 2011 significantly enhanced a negative feedback of Arctic sea ice loss on atmospheric circulation over the Aleutian region and central Eurasia during the ensuing wintertime, which could have led to the favorable atmospheric circulation that facilitated the occurrence of cold events resembling the one in 2012. This study also implies that the Aleutian low and disturbances in the midlatitudes over the northeastern Pacific may provide precursors that could increase skill in predicting the intraseasonal evolution of extreme cold events over Eurasia.
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