1998年长江流域洪水与海温异常关系的数值模拟研究

用IAP／LASG GOALS模式对1998年长江流域洪水与太平洋和印度洋海表温度异常之间的关系进行了数值模拟研究。利用观测的全年海表温度，模式能再现1998年夏季长江流域的暴雨，模式也能再现观测的1998年夏季西太平洋副高异常的基本特征。设计了一系列不同海区和不同时段的海温异常的敏感性试验。试验结果表明：印度洋海温异常是造成1998年长江流域洪水的主要因子；印度洋和西太平洋海温异常与西太副高的异常有更紧密的关系；夏季海表温度异常对1998年长江流域暴雨和西太副高异常的作用与冬春海温异常的作用相比要大得多。

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

With the IAP / LASG GOALS model, the relationships between the floods in the Yangtze River valley and 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 summer 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 effects of SSTA of different ocean areas on the floods, it is found that the SSTA in the Indian Ocean are a major 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.