华北夏季降水的年代际变化及其与东亚地区大气环流的联系

Inter-decadal Variation of North China Summer Precipitation and Its Relation with East Asian General Circulation

利用 1 90 0— 1 999年华北夏季降水、海平面气压和 1 950— 1 999年 NCEP月平均资料 ,借助小波变换研究了华北夏季降水的年代际变化特征 ,再用合成分析研究了华北夏季降水的年代际变化与东亚地区大气环流的联系。结果表明 :近百年华北夏季降水经历了 2 0世纪 3 0年代末之前和 40年代末到 70年代末两个多雨期阶段 ,2 0世纪 3 0年代末到 40年代末和 70年代末之后两个少雨期阶段。华北夏季少雨期 ,东亚夏季风偏弱 ,亚洲地区 50 0 h Pa高度场为正距平 ,副高脊线和北界位置偏南 ,贝加尔湖附近常伴有阻塞高压存在 。

Based on North China summer precipitation and sea level pressure from 1900 to 1999 and NCEP mean monthly data from 1950 to 1999, the inter-decadal variational character of North China summer precipitation is studied in virtue of wavelet transformation.Which in turn is used to study the relation between inter-decadal variation of North China summer precipitation and general circulation over East Asia by means of composite analysis.The results show that North China summers underwent two rainy periods from the beginning of 1900 to the end of 1930s and from the end of 1940s to the end of 1970s,and two less rain ones from the end of 1930 to the end of 1940s and from the end of 1970s to the end of 1990s in the last century.When North China summer precipitation is less,the East Asian Monsoon will be weaker with accompanied features of positive anomaly of 500 hPa geo-potential height field over the Asia,the ridge and northern borderline of sub-high to the south,and existing blocking high over Baikal.While it is vice versa if North China summer precipitation is richer.