华北5月降水年代际变化

Inter-Decadal Variations of Rainfall over North China in May

针对华北5月降水的年代际变化特征和成因,用华北5月降水资料、NCEP大气环流资料以及海表温度(SST)资料,采用EOF分析、相关分析、合成分析等方法研究了华北5月降水以及相关海区SST的年代际变化;结果表明从60年代中期至90年代初期华北5月降水存在明显的年代际变化,1965～1981年华北5月降水偏少,1982～1992年华北5月降水偏多;西太平洋暖池相比热带中东太平洋、热带印度洋对华北5月降水年代际变化有更明显的影响;当西太平洋暖池异常发展,热带中东太平洋、热带印度洋海温年代际变化处于暖位相,东亚上空为反气旋性环流异常场,东亚大槽较弱,副热带高压偏强偏西时,华北5月降水偏多;反之,副热带高压偏弱偏东时,华北5月降水偏少.

To investigate the inter-decadal variations of rainfall over North China in May, using the May rainfall data in North China, NCEP data and SST data, the inter-decadal variations of the rainfall over North China in May and related sea areas are studied based on EOF analysis, correlation analysis and composition analysis. The results indicate that the May rainfall in North China was less from 1965 to 1981, and richer from 1982 to 1993, i.e., the interdecadal variation of Rainfall in North China is obvious. The Western Pacific Warm Pool has more influence on the rainfall over North China in May than the tropic mid-east Pacific and the IndiaOcean. When the Western Pacific Warm Pool develops abnormally, the SST in the tropic mid-east Pacific and the India Ocean is in a warmer phase, an anticyclonic circulation anomaly lies over East Asia, the major trough over East Asia is shallower, the subtropicae high is stronger and extends west, the May rainfall in North China is richer, and vice versa.