中文摘要：

以2007年7月中、下旬中国中东部地区系列极端降水为研究对象,分别以NCEP/NCAR分析资料和中尺度气象模式（WRF）模拟输出驱动拉格朗日三维粒子输送模式（FLEXPART）,通过对极端降水有贡献的大气粒子群（气块）的后向轨迹,诊断了极端降水事件的水汽输送路径及其可能蒸发源区,并定量估算了不同水汽源区对降水事件的相对贡献大小。结果表明,极端降水事件的水汽输送可以向上游追溯到阿拉伯海和西亚地区,青藏高原的地形和副热带高压对水汽输送路径具有重要影响。源于热带和副热带低纬度地区的气块在到达降水区域之前,经历了多次的降水和蒸发过程,其中,阿拉伯海、印度半岛、孟加拉湾、中南半岛的缅甸以及中国西南部的川、滇等地区都是水汽的蒸发源区,上述所有源区为极端降水事件贡献了约80%的水汽。但是,不同水汽源区的相对贡献计算结果发现,陆地蒸发对水汽贡献相对重要,尤其是中南半岛的缅甸、中国的川、滇等地区的地表前期蒸发对这次极端降水的贡献超过了40%,这表明上游地区前期的土壤湿度异常可能对极端降水的发生具有重要的指示意义。

英文摘要：

In July 2007,a series of extreme precipitation events occurred over the middle and eastern parts of China,which caused the devastating flooding and considerable infrastructure damage and swept off many people.Based on the particle dispersion transport model FLEXPART,which is driven by the meteorological fields provided by the NCEP/NCAR analysis data and the outputs of the Weather Research and Forecasting（WRF） Model respectively,a very large number of particles（air parcels） trajectories were tracked backward.It initialized in a dense three-dimensional grid array located over the extreme rainfall region and was followed by determining the transport pathways of the moisture according to the precipitation during the event.As well the possible evaporative sources of the precipitation falling over the eastern part of China and their quantitative contributions were investigated.The ten days back-tracking analysis results show that this event was initially related with the transport of subtropical continental and tropical ocean moisture.During the process of transport,every air parcel might experience several periods of evaporation-precipitation in which it was significantly influenced by the combined action of the strong orographic enhancement of the Tibetan Plateau and the barrier of subtropical high pressure.Although the evaporation source was distributed over large parts of the areas,the major contribution to the precipitation is over the subtropical continent,including especially the Indian Peninsula,Myanmar and Sichuan and Yunnan Provinces over the southwestern part of China（approximately 40%）.This indicates that the abnormal soil moisture over the upstream areas provides with a good indication for the extreme precipitation.