华北春季降水及其与前期印度洋海温的关系

Spring Precipitation in North China and Its Relation to SST of Indian Ocean in the Preceding Winter

利用华北17站1951-2002年春季（3-5月）逐月降水资料和NOAA再分析海表温度资料，研究了华北地区春季降水特征及其与海温的关系。得知华北春季降水偏少年出现频次比偏多年频次高，但是年际变化明显，强度没有偏多年严重。华北地区春季降水有一定的年代际变化和周期性，降水周期在20世纪70年代中期以前为4-6a，在70年代中期以后为6-8a。同时用相关分析方法找出了影响华北地区春季降水的海温关键区为印度洋，发现印度洋在前一年11月到当年1月存在一个相关系数较高海区。用SVD方法证实了前期冬季印度洋海温正是与华北春季降水相关最显著的时段和地区。并用合成分析初步得到印度洋海温异常强迫影响大气环流，并通过遥相关影响华北地区降水。

Using monthly NOAA reanalysis SST and rainfall data at 17 stations in North China during the spring （ MAM ） of 1951-2002, features of spring rainfall in North China and its relationships with SST are investigated. The results indicate that the frequency of negative rainfall anomaly is more than that of positive anomaly, but the intensity of positive anomaly is stronger. The interannual, interdecadal and periodic variations of spring rainfall series are obvious,and the period of rainfall is about 5 years before 1975 ,and about 7 years after 1975 respectively. Using correlation analyses method, we have found that there is a higher correlation coefficient sea area in the Indian Ocean and Eastern Equatorial Pacific, and the Indian Ocean＇ s SST in previous November to this year＇ s January significantly impacts the next spring rainfall anomaly in North China. Then it is confirmed by the SVD method that the last winter SST of the Indian Ocean is the most significant factor which affects the spring precipitation of North China. Based on composite analysis, we know the SSTA affects the atmosphere circulation and precipitation of North China by teleconnexion.