华北地区春季和夏季降水特征及与气候相关的分析

The Character of Precipitation and Its Relation to Climate Change over North China in Spring and Summer

利用美国NCEP再分析月平均资料及我国华北地区25个气象站1951-2003年53年的月降水资料，研究了华北春季和夏季降水的年代际和年际变化特征及与大气环流的联系。结果表明，华北春季和夏季的年代际和年际变化特征有一定的差别，春季降水存在3种典型降水类型，即“全部一致型”、“东西型”和“东北西南型”。第一特征向量为主导，其时间变化系数与春季降水量特征基本一致，说明华北春季降水主要受西北气流影响，具有降水偏多（少）一致性特征。降水偏多、偏少年异常场差值显示春季华北主要受东亚上空的异常反气旋环流影响，其底部偏东气流在南海、台湾海峡一带转向向北一直吹到华北。华北夏季降水存在3种典型降水类型，即“全部一致型”、“南北型”和“东西型”。降水偏多、偏少年异常场差值显示夏季华北受副高西侧西南气流的影响从印度孟加拉湾携带大量水汽从西南方向吹向华北，带来较多的降雨。

With the data of monthly precipitation of 25 stations in North China and NCAR/NCEP monthly reanalysis atmosphere variables, we have investigated the variation features of precipitation in North China at interdecadal and interannual time scales, and also its relation with the atmospheric circulations in the Northern Hemisphere in spring and summer. The results show that 1） The variation features of precipitation in North China have some differences between spring and summer. 2） The spatial and temporal structure features and changes of precipitation in spring have three typical precipitation structures in the region, that is ＂All-Consistency＂, ＂West-East＇, ＂Northeast-Southwest＂. 3） The first eigenvector is the dominant type. Its time coefficient has same change as precipitation. This shows that the precipitation in North China is controlled by northwest windstream and the precipitation has more or less consistency. 4） The D-value of abnormal field about more or less year shows that the abnormal anticyclone in the east of Japan affects the North China in spring, its eastern air flow changes to North in South China Sea and Taiwan Strait. 5） In summer, the spatial and temporal structure features and changes of precipitation have three typical precipitation structures in the region, that is ＂All-Consistency＂, ＂North-south＂, ＂West-East＂ . 6） The D- value of abnormal field about more or less year shows that the southwest windstream of the abnormal subtropical anticyclone affects the North China in summer; its southwestern air flow carries lots of water vapor to North China,which brings large quantity of rainfall.