Numerical simulation of the relationships between the 1998 yangtze river valley floods and SST anomalies

Abstract

With the IAP/LASG GOALS model, the relationships between the floods in the Yangtze River valley arid sea surface temperature anomalies (SSTA) in the Pacific and Indian Oceans in 1998 have been studied. The results show that the model can reproduce the heavy rainfall over the Yangtze River valley in the sum-mer of 1998 forced by global observational sea surface temperatures (SST). The model can also reproduce the observed principal features of the subtropical high anomalies over the western Pacific. The experiments with the observed SST in different ocean areas and different periods have been made. By comparing the ef-fects of SSTA of different ocean areas on the floods, it is found that the SSTA in the Indian Ocean are a ma-jor contributor to the floods, and the results also show that the SSTA in the Indian Ocean and the western Pacific have a much closer relationship with the strong anomalies of the subtropical high over the western Pacific than the SSTA in other concerned areas. The study also indicates that the floods and subtropical high anomalies in the summer of 1998 are more controlled by the simultaneous summertime SSTA than by SSTA in the preceding winter and spring seasons.