关键词: 叶片面积, 叶片面积, 数字照片解析法, 坐标纸法, 复印比重法

Abstract: Using of the daily precipitation data of 89 stations in South china from the national meteorological information Center and the reanalyzed monthly average 850hPa wind field from the National Centers for Environmental Prediction and the National Center for Atmospheric Research, as well as extend reconstruction monthly sea surface temperature (SST) data form National Oceanic and Atmospheric Administration between 1969 and 2013, the spatial-temporal features and influence factors of extreme precipitation during the pre-rainy season in South China were researched .The main conclusions are as follows. (1) The interannual variations of the pre-rainy season extreme precipitation of South China are significant. Most areas in South China are consistent anomaly，except for the central and south of Guizhou, Since the 1990s, particularly in Guangdong, south Guangxi, the north and central of Fujian, and central and south Guizhou，where the risk of extreme precipitation is high. (2) The main reasons of the interannual variations of extreme precipitation in South China are ENSO-like sea surface temperature anomaly (SSTA) and the corresponding atmospheric circulation anomaly. From the preceding winter to the pre-rainy season, ENSO-like SSTA has the percentage decrease, however, the ENSO-like positive SSTA sustainably regulates the South China Sea and western Pacific anti-cyclonic airflow to impact on the South China Sea, which increases the warm and humid vapor input to South China and causes extreme floods in pre-rainy season of South China, And vice versa.