西北地区春季和夏季降水异常特征分析

Analysis of Anomalous Characteristics of Spring and Summer Precipitation in Northwest China

用EOF分析方法选取西北地区29个代表站,分别对其春季和夏季近50a降水进行年际变化和年代际变化时空特征分析,发现西北地区近50a降水时空趋势变化以103°E为基准线,以西为正,以东为负,并有准3a的振荡周期;20世纪80年代中期西北地区春季降水出现了气候突变,西北地区多、少雨与500hPa高度场和副热带高压的位置和强弱密切相关。

29 representative stations in Northwest China are selected using EOF analysis,and the temporal and spatial characteristics of the interannual and interdecadal variations of 50-year spring and summer precipitation are analyzed.It is found that the tendency of precipitation in northwest China is positive to the west of 103°E longitude and negative to the east.And there are a quasi-three years periodic oscillation of precipitation and a sudden change in the spring precipitation in the middle 1980's in northwest China.The above results indicate that the wet/dry phase of climate in northwest China is close related with the 500hPa height field and the location and intensity of subtropical high.