Abstract:

Based on daily precipitation data，FY － 2E satellite data and NCEP/NCAR reanalysis data，the rainfall process occurred from 13 to 16 January 2012 in South China was analyzed，and the water vapor transport source and dynamic mechanism of the tropical water vapor plume and their relationship with precipitation were studied． The results showed that，the tropical water vapor plume represented the upper and middle levels water vapor transport from the Bengal Bay，and it actually reflected the transmission and convergence of the entire level water vapor in troposphere． Meanwhile，the low － level water vapor come from the South China Sea contributed to continuation of the water vapor plume and formation of the heavy rainfall． The Coupling of Jet in front of the upper trough and low －level shear line prompted the formation of upward motion，and leaded to the precipitation． However，the upper jet moved and steered from NE － SW to ENE －WSW owing to the moving and filling up of upper trough led the water vapor plume to move toward the east in the late period of rainfall，and the water vapor band eventually was set apart from Bengal Bay． In the rainfall process，there was not strong convective clouds appeared on the tropical water vapor plume，but the heavy rainfall happened in the good water vapor transport condition and a weak upward motion．

Key words:  cold － seasonal precipitation, tropical water vapor plume, water vapor image

摘要：

利用逐日降水量资料、 FY －2E 卫星资料以及 NCEP/NCAR 再分析资料， 对 2012 年 1 月 13 ～16 日的一次南方冷季降水过程进行分析， 剖析了热带水汽羽形成的水汽输送源和动力机制， 及其与降水的关系。分析表明， 热带水汽羽不但表征了中高层孟加拉湾水汽的输送， 它实际上反映了对流层整层水汽的输送、 辐合， 低层南海水汽输送带为水汽羽的维持和降水的产生做出了贡献;高空槽前急流与低空切变线的耦合促使了上升运动的形成， 导致降水的产生。后期高空槽的移动填塞致使急流轴发生移动及转向， 从而引导了热带水汽羽的移动， 最终导致热带水汽羽的断裂消亡;热带水汽羽上不存在强对流云团， 未形成强对流过程， 但由于水汽输送条件较好， 配合弱的上升运动产生了这次强降水过程。

关键词: 冷季降水, 热带水汽羽, 水汽图像