The Coupling Relationship Between Summer Rainfall in China and Global Sea Surface Temperature

By using the monthly rainfall in 160 stations of China and the sea surface temperature(SST) data from NCEP/NCAR,the spatial and temporal distributions of summer(JJA) rainfall and their correlations with SST are analyzed.The coupling relationship between the anomalous distribution in summer rainfall and the variations of SST has been studied with the Singular Value Decomposition(SVD) analysis.The results show that there are mainly three patterns in the anomalous distributions of summer rainfall.Their temporal variations present the time scales of not only interannual but also interdecadal.Especially,the rainfall in North China decreases from about 1965 and more obviously after 1976.The coupling relationship between the summer rainfall and global SST with SVD analysis presents a dominate time scales of interdecadal variation.The remarkable decrease of summer rainfall in North China and southern part of Northeast China after 1976 has been shown to be closely associated with the SST anomalies in Pacific Ocean,Indian Ocean and the tropical and south of Atlantic Ocean.Particularly,the SST becomes warmer obviously from 1976 in the tropical central and eastern Pacific Ocean,nearly the whole Indian Ocean and the tropical and south of Atlantic Ocean.The relationship between persistent drought in North China and the interdecadal variations of SST in Indian and Atlantic Oceans has not been revealed before.The coupling relationship between the summer rainfall and SST has also been presented in the significant correlations between the rainfall anomalies in the middle and lower reaches of the Yangtze River and the SST anomalies in the Pacific and Atlantic Oceans.When the SST anomalies are positive in South China Sea,Kuroshio region and the neighbouring area,and in the tropical and north of Atlantic Ocean,and negative in the tropical central and eastern Pacific Ocean,the rainfall in the middle and lower reaches of the Yangtze River tends to be above normal.In the reverse situation,the rainfall tends to be below(normal.)