冬季极涡的长期预报

LONG-RANGE FORECAST FOR WINTER POLAR VORTEX

利用北半球500hPa 高度场及北太平洋海温场资料,进行统计分析,重点讨论了对我国气温影响颇为显著的冬季Ⅰ区极涡面积指数的预报问题。结果表明:前期3月北大西洋西风环流及5月北美大槽强度对冬季Ⅰ区极涡强弱变化具有很好的指示性。Ⅰ区极涡异常强弱年份,北太平洋海温距平分布表现出截然相反的两种类型。北太平洋中南部地区海温经向差及北太平洋中西部地区海温纬向差对Ⅰ区极涡面积具有显著影响。

Using the Northern Hemisphere 500hPa altitude data and North Pacific sea temperature da-ta,the forecasting of winter polar vortex area index for I area,which would affect air temperatureof China significantly,is conducted.The results show that the intensities of North Atlantic westwind circulation in prior March and North American big trough in May are good indication of thewinter ploar vortex intensity change.When the polar vortex is anomalous strong or weak theNorth Pacific sea temperature anomaly patterns are opposited.And,the sea temperature meridion-al balance in the mid-South Pacific and sea temperature zonal balance in the mid-west of NorthPacific would influence the polar vortex area index significantly.