利用美国国家环境预报中心(NCEP)再分析资料以及晋北地区18个台站1960-2008年夏季降水资料,通过M-K突变曲线、滑动t检验、累积距平3种气候突变检验方法对晋北地区夏季降水的统计检验结果均表明,夏季降水在1996年发生了由多到少的转折。线性趋势法分析晋北地区夏季降水表明:夏季降水呈负的线性趋势,说明自1960年以来晋北地区夏季降水一直处在减少的趋势,干旱较为明显,尤其是广灵、平鲁、灵丘干旱趋势更为严重。对晋北夏季多雨、少雨年的大气环流异常特征进行了合成分析,结果表明:欧亚中高纬位势高度异常直接影响着晋北地区夏季降水的异常,多(少)雨年夏季500hPa位势高度呈现出“负(正)-正(负)-负(正)”的分布特征,中高纬地区以经(纬)向环流为主,冷空气活动频繁(偏弱),晋北地区处在槽(脊)的东南部,有利于降水偏多(少)。对流层低层流场多雨年西太平洋有暖湿气流向北输送,直达蒙古到东北一带与西伯利亚分裂下来的弱冷空气在华北地区相遇,有利于晋北地区夏季降水偏多。少雨年水汽条件差,不利于降水。 Based on the NCEP reanalysis data and summer precipitation data from 1960 to 2008 at 18 stations in the north of Shanxi Province, three kinds of climatic abrupt change test methods, MK mutation curve, sliding t test and accumulated anomaly, The results of statistical tests on summer precipitation all showed that the summer precipitation had more or less turned away in 1996. Linear trend analysis of summer precipitation in northern Shanxi shows that summer precipitation has a negative linear trend, indicating that summer precipitation in northern Shanxi has been decreasing since 1960 and the drought is more obvious, especially in Guangling, Pinglu, Lingqiu Drought trends are even worse. The results show that the geopotential height anomalies in the middle and high latitudes of Eurasia directly affect the summer precipitation anomalies in the northern part of Shanxi Province, and the 500hPa geopotential (+) Distribution in high altitude, high (-) circulation in the middle and high latitudes and frequent (weak) cold air activities in the northern part of Shanxi Province Located in the southeast of the trough (ridges) is conducive to more (less) precipitation. In the rainy year, the convective lower troposphere has warm and humid flow to the north in the rainy year. The weak cold air that divides directly from Mongolia to the northeast and Siberia breaks down in North China, which is favorable for the summer precipitation in the northern part of Shanxi Province. Poor water vapor conditions in less rain, is not conducive to precipitation.