The Character of Precipitation and Its Relation to Climate Change over North China in Spring and Summer
华北地区春季和夏季降水特征及与气候相关的分析

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.