A Study on the Coupling Relationships among the Pacific Sea Surface Temperature and Summer Rainfalls over North China and India

Based on 1951-2014 reanalysis and observational datasets, the coupling relationships among the summer rainfalls over North China (NCSR) and India (ISR) and global sea surface temperature (SST) are analyzed. With the multivariate empirical orthogonal function (MEOF) method, the dominant coupling modes among NCSR, ISR and SST have been identified. The results show that there exist significant coupling relationships among them on the interannual scale. The NCSR and ISR tend to increase/decrease synchronously under La Niña/El Niño condition with cooler/warmer SST over the central and eastern equatorial Pacific in the concurrent summer. However, such a relationship between NCSR and ISR does not always hold. If the SST pattern is in the decaying phase of the El Niño event from the preceding winter to spring, summer rainfall over western India increases but the NCSR is likely to decrease. It is accompanied by the weakening of the positive phase of Indian Ocean Dipole (IOD) from the preceding winter, which weakens the East Asia summer monsoon in the concurrent summer. In addition, the circumglobal teleconnection pattern (CGT) connecting ISR and NCSR is inactive, since the above-normal ISR mainly occurs over western India. These results are helpful for in-depth understanding of the role SST plays in the relationship between the summer rainfalls over North China and India, and thus provide some clues for the prediction of North China summer rainfall.