中文摘要：

利用1979—2011年广东省86个测站的地面观测逐日降水资料及NCEP-DOE第二套分析资料,分析广东前汛期及其各月暴雨的水汽输送来源及其异常特征,诊断持续性暴雨过程水汽输送异常随赤道MJO活动的变化。结果表明,从多年气候平均场来看,广东前汛期（4—6月）水汽输送来源主要有孟加拉湾经中南半岛向华南输送（即西南支输送）、源于热带西太平洋随副热带高压边缘气流经南海地区向北输送（即东南支输送）和源于青藏高原西南侧伴随南支西风气流的向东输送（即西支输送）。广东前汛期降水异常变化的水汽输送异常来源与气候平均来源有所不同,前汛期暴雨的水汽输送异常主要是东南支、西支输送的输送异常以及源于我国中低纬度地区随偏北异常气流向南的水汽输送（简称北支输送）异常这三方面,其中北支输送异常主要加强广东区域的水汽通量辐合。暴雨水汽输送异常存在月际变化,西支和北支输送异常是4月、5月、6月暴雨的共同点,另外,5月暴雨还包括西南支、东南支输送异常,6月暴雨则包括东南支输送异常。各月持续性暴雨（持续3 d或以上的暴雨）与非持续性暴雨的水汽输送异常有所不同,4、5、6月东南支水汽输送异常,持续性暴雨比非持续性暴雨明显偏强。6月广东持续性暴雨的西南支水汽输送异常随MJO活动产生一定的变化,在MJO第4、5、6、7位相（8、1、2、3位相）,西南支水汽向华南输送偏强（弱）。赤道MJO活动影响西南支水汽输送强度的物理过程,主要是通过改变大气经向热力对比来影响孟加拉湾西南季风强弱变化,从而使该支气流流向华南的水汽输送发生变化。

英文摘要：

The characteristics of water vapor transport and its anomaly for torrential rain during the annually first rainy season （April-June） and each month of the year in Guangdong were analyzed using 86-station observational daily precipitation of the province and daily atmospheric data from NCEP-DOE Reanalysis 2 during 1979--2011. Besides, the variation of water vapor transport anomaly with MJO activity was diagnosed further. It was shown that the climatological water vapor during the rainy season is mainly transported from （1） the Bay of Bengal through the Indochina Peninsula to Southern China （namely the southwest transport）, （2） the tropical western Pacific in a northward route with the edge flow of the subtropical high through the South China Sea （namely the southeast transport）, and （3） the southwestern side of Tibetan Plateau in an eastward route with the southern branch of the westerlies （namely the westward transport）. Anomalous origin of water vapor transport for anomalous rainfall is different from that of climatological mean. Anomalous water vapor transport for torrential rain is primarily via the southeast branch, west branch and north branch of transport anomaly, which originates from mid-low latitudes of China with north wind anomaly. The north branch intensifies the convergence of water vapor flux, and is not an actual water vapor source. Anomalous water vapor transport for torrential rain changes with the month. The west and north branches are commonly shared by the torrential rain in April, May and June. Moreover, the southwest and southeast branches contribute to the torrential rain in May, and the southeast branch contributes to that of June. Water vapor transport anomaly for sustained torrential rain （lasting for 3 days or more） is different from that of 1- or 2-day torrential rain in each month. For sustained torrential rain, the southeast branch is much stronger than that for the 1- or 2-day torrential rain in April, May and June. The southwest branch for sustained