The Interdecadal Variation of North Polar Vortex and Its Relationships with Spring Precipitation in China
北极涡年代际变化及其与我国春季降水的关系

The area size and intensity of 500 hPa north polar vortex and four quadrants are estimated based upon 54-year NCEP/NCAR reanalysis monthly mean geopotential height data.By means of linear trend estimate,Morlet wavelet analysis and binomial coefficient smooth,the interdecadal variation characteristics of north polar vortex and spring precipitation in China are studied.The results show that:1)Seasonal average area and intensity of polar vortex exists obvious inter-decadal variation.Before the middle age of the 1970s,area size of north polar vortex trended to rise,and after that,it trended to minish,but during the size had a linear decline trend as a whole.The center of polar vortex mainly displaced towards Asia-Europe during the early and middle age of the 1960s,while trended to the Pacific and the Atlantic after the middle age of the 1990s.2)Spring average precipitation of the 160 station in China obviously increased thrice and decreased four times.The trend of spring precipitation in South and Southwest China is opposite to the Yangtze River and Yellow River valleys.During the early and middle age of the 1960s and in early and late period of the 1990s,the precipitation was more in the Yangtze River and Yellow River valleys,but during telophase of the 1980s,middle age of the 1990s and the beginning of the 21st century,the precipitation is more in South and Southwest China.3)If the area of polar vortex in quadrant II is bigger than normal,and intensity of polar vortex in quadrant I and III is weaker in spring,the precipitation is below the normal in the middle drainage area of between the Yangtze River and the Yellow River,and it exceeds the normal in the seaside area of Guangdong and Fujian.Polar vortex in winter influences more obviously next spring precipitation than the vortex of in summer and autumn,especially for polar vortex in North America and the Atlantic-Europe sections.