Analysis of the Role Played by Circulation in the Persistent Precipitation over South China in June 2010

South China (SC) experienced persistent heavy rain in June 2010. Theclimatic anomalies and related mechanism are analyzed in this study. Resultsshow that the large-scale circulation pattern favorable for precipitationwas maintained. In the upper level, the South Asian High and westerly jetstream provided a divergent circulation over SC. In the middle and lowlevels, an anomalous strong subtropical high (STH) extended to the SouthChina Sea. The southwesterly monsoon flow along the northwest flank of theSTH transported abundant water vapor from the western North Pacific, the Bayof Bengal, and the South China Sea to SC. The precipitation can beclassified into two types: the West Siberia low (WSL)-induced low-levelcyclone mode, and the STH-induced low-level jet mode. STH and WSL indicesare defined to estimate the influence of these two systems, respectively.Analysis shows that both are critical for precipitation, but theirrespective contributions differ from year to year. In 2010, both wereimportant factors for the heavy rainfall in June.