对西北区东部典型伏秋干、湿年成因进行了动力诊断,得出典型伏秋干年500hPa高度场上西北区上空为正距平区,风矢量场表现为反气旋加强区,垂直速度为下沉运动区,比湿为负距平,赤道东太平洋区(5°S~5°N,170°E~120°W)海温为正距平区,黑潮区和西风漂流区海温均为正距平,白令海为正距平;而典型伏秋湿年则相反。表明西北区东部伏秋干年和湿年北半球500hPa环流、比湿、风矢量、垂直速度场和赤道海温场具有近乎相反的异常特征。这是形成西北地区东部伏秋干湿年的重要物理原因。这些结果作为短期气候预测的气候背景有重要的参考意义。

The cause of anomaly drought and wet years in summer and autumn in east of Northwest China was studied by method of dynamical diagnose.The result showed that the wind vector field appears intensive anticyclone field, vertical velocity was sinking motion, specific humiditywas negative departure on 500 hPa geopotential height in typical drought year in Northwest China, the temperature of Bering sea and sea of equatorat 5°S~5°N, 170°E~120°W were positive departure, but the sea temperature of Kurushio and westerly float field were negative departure.While these results in typical wet year were just opposite.All these indicated that circulation, specific humidity, wind vector, vertical velocity field and equator sea temperature field of drought years in summer and autumn were opposite to that of wet years on 500 hPa geopotential height in Northwest China, which were main physical causes that promoted to form drought and wet years.