西南地区夏季旱涝与厄尔尼诺(拉尼娜)的关系分析

The Correlation Analysis between Summer Droughts & Floods in the Southwest and ENSO

利用中国西南地区多个站点1951--2008年夏季逐月降水资料，1951--2008年的厄尔尼诺（拉尼娜）指数（Nin03．4），对西南地区夏季旱涝与厄尔尼诺（拉尼娜）的相关联系进行了分析，得出以下结论：前期厄尔尼诺（拉尼娜）指数与中国西南地区的夏季降水存在一定的相关关系，如云南的中部，西部和南部，广西的西北部和贵州中部，东南部呈弱的负相关，除这几个地区都是呈现正相关。整个西南地区的相关系数，南部呈负正负，北部呈正的强弱强分布。合成分析表明：厄尔尼诺或拉尼娜事件发生后的夏季，西南地区降水距平基本呈现相反的分布特征。厄尔尼诺事件发生后，西南地区夏季降水较多，易造成涝灾；拉尼娜事件后，西南地区夏季降水较少，易造成旱灾。

This article utilizes the information on monthly rainfall in the summer, and the ENSO index （Nino3.4） from 1951 to 2008 from various sites in the Southwest in our country, then analyzes the correlation between summer drought in the Southwest and ENSO, finally draws the following conclusions： in early times, ENSI9 index presented certain correlation with the rainfall in the Southwest in our country, e.g. it showed negative correlation in central, western and southem Yunna_n, northwestern Guangxi and central and southeastern GuiZhou, while other areas showed positive correlation. As for the correlation coefficient of the entire Southwest, the southern part presented a ＂negative-positive-negative＂, and the western showed a ＂strong-weak-strong＂ distribution. Combining analysis indicts that the summer rainfall distribution of the .southwest in China shows opposition characters. After the E1 Nino Events, the Southwest shows more rainfall in summer, getting more humid, thus floods were likely to occur; however, after the La Nina Events, the Southwest shows less rainfall in summer, getting drier, thus droughts were likely to occur.