近111年来东亚夏季风的变异及其与中国降水的关系

根据1899～2009年北半球月平均海平面气压场资料,计算近111年来东亚夏季风强度指数,分析了东亚夏季风的年代际及年际变化特征。结果表明,20世纪20年代东亚夏季风达最强,80年代中期以后东亚夏季风强度一直呈减弱趋势,其中21世纪初达最弱。Morlet小波分析发现,东亚夏季风年代际及年际变化中存在准10年和准2年显著性周期。我国东部降水的年际变化与东亚夏季风的强度变化密切相关,强（弱）东亚夏季风年份,长江中下游地区降水量比常年偏少（偏多）;而华北地区降水量比常年偏多（偏少）。东亚夏季风减弱是造成20世纪80年代中期以后华北地区干旱少雨,长江中下游地区洪涝多雨的一个重要原因。

Variation of East Asian Summer Monsoon and Its Relationship with Precipitation of China in Recent 111 Years

Based on the monthly average SLP data in the northern hemisphere from 1899 to 2009, East Asian summer monsoon intensity index in recent 111 years was calculated, and the interdecadal and interannual variation characteristics of East Asian summer monsoon were analyzed. The results showed that East Asian summer monsoon in the 1920s was the strongest. The intensity of East Asian summer monsoon after the middle period of the 1980s presented weakened trend. It was the weakest in the early 21st century. Morlet wavelet analysis found that the interdecadal and interannual variations of East Asian summer monsoon had quasi-10-year and quasi-2-year significance periods. The interannual variation of precipitation in the east of China closely related to intensity variation of East Asian summer monsoon. In strong (weak) East Asian summer monsoon year, the rainfall in the middle and low reaches of Yangtze River was less (more) than that in common year, while the rainfall in North China was more (less) than that in common year. The weakening of East Asian summer monsoon was an important reason for that it was rainless (drought) in North China and rainy (flood) in the middle and low reaches of the Yangtze River after the middle period of the 1980s.