中文摘要：

通过统计分析和区域气候模式RegCM3的模拟试验，对热带西太平洋关键区潜热通量异常影响华南6月旱涝的机制进行研究。结果表明：（1）华南6月的降水与热带西太平洋5月和6月的潜热通量都存在负相关关系，特别是与5月热带西太平洋关键区的潜热通量存在更为显著的滞后负相关。（2）热带西太平洋关键区潜热通量异常是影响华南6月旱涝的重要因子，其概念模型是：5月和6月热带西太平洋潜热通量异常增高，在其西北侧对流层低层出现一个异常的气旋性环流，华南地区位于气旋性环流西侧，为东北风异常，不利于西南季风进入我国华南地区，水汽减少。同时，形成一个潜热通量异常区上升、而在华南地区下沉的垂直环流，华南降水减少，导致干旱发生。当5月和6月热带西太平洋潜热通量异常减少，在其北侧出现异常反气旋式环流，华南地区处于环流西侧，西南气流加强，有利于水汽输送。同时，出现一个热带西太平洋潜热通量区下沉、而华南地区上升的距平垂直环流，造成华南地区洪涝多雨。

英文摘要：

According to synthetic analysis and numerical simulations using a regional climate model （RegCM3）, this paper analyzed the impact of the latent heat flux anomaly in the tropical westem Pacific on the precipitation over the south of China in June. The results are as follows. （1） Correlation analysis shows that the south China precipitation in June is negatively dependent on the latent heat flux of the tropical western Pacific in May and June, especially in May. The south China precipitation in June appeared to negatively correlate with low-level relative vorticity in the latent heat flux abnormal area of the tropical western Pacific. （2） The latent heat flux anomaly in the tropical western Pacific is the vital factor affecting the flood and drought of South China in June. A conceptual model goes like this： When the latent heat flux in the tropical western Pacific is abnormally increased （decreased）, an abnormal cyclone （anticyclone） circulation is formed at the low-level troposphere to its northwest. As a result, an abnormal northeast （southwest） air flow affects the south of China, being disadvantageous （advantageous） to water vapor transported to the region. Meanwhile, there is an abnormal anticyclone （cyclone） at the low-level troposphere and an abnormal cyclone （anticyclone） circulation at the high-level troposphere in the region, which is advantageous for downdraft （updraft） there. Therefore a virtual circulation forms updraft （downdraft） in the abnormal area of latent heat flux and downdraft （updraft） in the south of China, which finally leads to the drought （flood） in the region.