Based on the two-dimensional indices of atmospheric blocking and manual identification method,the events of the blocking high(BH)alone and BH together with the Arctic High(AH)in the Eurasian region in the winter of 1979-2020 were studied.And the basic characteristics of AH in blocking events and its influence on cold air in winter in China were analyzed.The results showed that,when AH was connected with BH,the high pressure center was mainly located near Novaya Zemlya,and there were more blocking events in the Ural Mountains than in the Baikal Lake.The frequency of blocking events was the highest in January,and significantly lower in the 1990s than in other decades.Since beginning of the 21st century,the proportion of total blocking events accompanied by AH had increased significantly,by about 40%.When AH affected the winter cold air in China through BH,the troposphere in Eurasia was abnormally warm in high latitudes and abnormally cold in mid-latitudes.The westerly wind in the mid-latitude region weakened and the subtropical jet strengthened.The occurrence of the anticyclonic Rossby wave breaking enhanced the potential vorticity circulation in Eurasia,and AH was maintained and developed.A relatively stable"two troughs and one ridge"flow pattern was formed at 500 hPa,and the center of the high pressure was northerly and stronger.This circulation was conducive to the formation and development of surface Siberian high,which was located north and east,and the influence range was large.The cold air invaded China in an east path and the northeast region was affected earlier.
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