| The daily precipitation data at 734 stations in China, is applied to analyze thespace-time features of the rainstorm and characteristics of flood/drought inpre-summer flood period (AMJ) over South China during 1958-2004. And it alsostudied the space-time distributions of the rainstorm in flood years and drought yearsthat were selected according to the flood/drought indexes. Furthermore, we mainlydiscussed the background of climatic anomalies about rainstorm in flood/droughtyears and the large-scale circulation features of the continuous rainstorm inpre-summer flood period.From the analysis, the results are summarized as follows:1. The space-time distributions of rainstorm in pre-summer flood period overSouth China is uneven and there is a period of 2～4 years in rainstorm days change.2. The drought and flood change in pre-summer flood period is closed to thenumber of rainstorm. Rainstorm was less (more) in the drought (flood) years. In floodyears, rainstorm was mostly happened in the middle of Guangdong province.3. The flood/drought and rainstorm anomalies in pre-summer flood period areclosely related to west Pacific subtropical high, east Asia trough, polar vortex andsouth Asia high on the corresponding period. The change of SST during lastDecember to February in the tropical west Pacific Ocean is significant precursorsignal to the rainstorm days pre-summer flood period over South China.4. The west Pacific subtropical high has an important impact on the continuousrainstorm in pre-summer flood period.
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