中文摘要：

利用中国160个台站降水资料和ERA-40再分析资料分析了华北地区夏季降水及其对应的大气环流年代际变化特征。分析结果如下:华北地区夏季降水自1977年之后明显减少,出现持续性干旱。1977～2000年500hPa高度场出现与1966～1976年相反的遥相关波列;华北地区上空700hPa出现反气旋型环流异常,并出现明显偏北风异常,且下沉气流加强,水汽出现辐散;此外,200hPa高度上西风带偏南且减弱。相反,1966～1976年华北地区上空700hPa出现气旋型环流异常,并出现偏南风异常,且上升气流加强,水汽输送辐合;此外,200hPa上西风异常偏北加强。

英文摘要：

Due to the importance of persistent droughts in North China after 1977,the circulation anomalies pattern causing the persistent droughts in North China are analyzed by using observed data and ERA-40 reanalysis data.The analyzed results show that interdecadal variability of summer precipitation in China is very obvious.From 1977 to 2000,summer precipitation obviously decreased and the persistent droughts occurred in North China and the Yellow River basin.After 1977,a teleconncetion wave-train is opposite to ...