ENSO与中国东部夏季降水异常关系的年代际变化

Interdecadal variation of the relationship between ENSO and East-China summer rainfall

根据1960—2011年Had ISST资料集中的月平均海表温度资料和中国753站逐日降水资料,基于转经验正交函数分解等分析方法,发现中国夏季降水的变化具有明显的独立性特征,可以分为相对独立的11个雨区,并在此基础上讨论了11个雨区夏季降水与ENSO的相关关系及其年代际变化,发现不同雨区的夏季降水与ENSO相关关系的年代际变化特征不尽相同,据此可分为3种类型:第1类为稳定不相关型,代表区为东北地区、长江中下游地区、江南地区、闽赣地区、环琼州海峡地区;第2类为稳定相关型,代表区为河套地区、黄河中下游地区;第3类为相关关系变化型,代表区为辽吉地区、黄淮地区、淮河流域以及两广地区。而在第3类相关关系变化型中,4个雨区夏季降水与ENSO相关关系的年代际突变时间也存在差异,两广地区的突变年份在1975年左右,辽吉地区和黄淮地区的突变年份在1980年左右,淮河流域的突变年份在1985年左右。

In this study,based on the monthly sea surface temperature data and daily rainfall of753stations over China,11subdivisions of summer rainfall in eastern China were found by using the rotated empirical orthogonal function(REOF),and other methods.The11subdivisions of summer rainfall were shown by statistical methods to be independent from each other,which differs from the three types of summer rainfall patterns of eastern China,thus representing the connection of summer rainfall in eastern China.Based on the interdecadal variation of the relationship between ENSO and11subdivisions of summer rainfall,three categories of the correlation between SSTA in the Nio3region and summer rainfall were defined by means of moving correlation,composite analysis,etc.:In the first category,the correlation is always very week in the long term,such as in northeastern China,the middle and lower reaches of the Yangtze River,south of the Yangtze River,the Fujian Jiangxi area,and the Qiongzhou Rim strait.In the second category,the significant correlation is fairly stable,such as in the Hetao area and middle and lower reaches of the Yellow River.In the third category,the relationship shows noticeable changes,as such as in the Liaoning Jilin,Yellow River Huaihe River,Huaihe River and Guangdong Guangxi areas.In the fourth category,the abrupt year of the interdecadal variation of the relationship between ENSO and four subdivisions of summer rainfall in eastern China differ.The correlation between SSTA in the Nino3region and the summer rainfall in the Guangdong Guangxi area abruptly changed in1975.However,the relationship between ENSO and summer rainfall in the Liaoning Jilin and Yellow River Huaihe River areas was weak after1980.The interdecadal variation of the relationship between ENSO and summer rainfall of the Huaihe River occurred around1985.