Analysis of the Characteristics and Causes of Interdecadal Changes in the Summer Extreme Precipitation over Eastern China

Using daily precipitation data from eastern China, in this study, we investigated the interdecadal shift in the summer extreme precipitation (SEP) and analyzed the characteristics before and after the climate shift. We also analyzed the cause from the perspective of different responses to global warming between land and ocean, which leads to circulation adjustments. The results show that the SEP in eastern China exhibited an obvious interdecadal shift around 1990, after which it became a positive anomaly. Compared with the SEP before the shift, the distributions of major modes shifted south, the intensity of SEP was enhanced, and the contribution rate to summer precipitation increased in both South and East China, whereas in North China all of these factors exhibited the opposite change. The change in the temperature difference between land and ocean caused by the strong positive anomaly of the sea surface temperature in the western Pacific warm pool is one of the important factors driving this shift, leading to the interdecadal adjustment of the East Asia summer monsoon system. In the low–middle latitudes, the intensity of the summer monsoon weakened, the West Pacific subtropical high strengthened and moved south, and the South China Sea high was also enhanced. In the middle–high latitudes, this cyclonic anomaly was broken and the East Asia Trough strengthened. Under the influence of this circulation adjustment, the water vapor decreased (increases) and vertical motion weakened (is enhanced) in North China (South and East China). Thus, the SEP decreased in North China and increased in South and East China.