中文摘要：

对2007—2011年梅雨期江淮流域降水进行统计分析,确认此时段降水频次与降水量空间分布在淮河与长江中下游,形成两个分离的多降雨区。长江与淮河两分离雨带在盛行中尺度系统、空间结构、梅雨锋位置、水汽输送通道、暴雨落区、干冷气团入侵以及干冷动量南移等方面,均有各自特征。在主导高空环流下,更多低涡暴雨（77%）位于长江流域,更多辐合线暴雨（86%）发生在淮河流域,这些盛行的浅薄降水系统,造成梅雨暴雨雨强大、风速小的特征。长江流域低涡环流引导水汽输送来自南海与东海两地,因而暴雨范围更大,雨带更宽,而淮河流域辐合线主要水汽来源仅为南海。假相当位温表现的梅雨锋作为干冷空气的前缘,在淮河流域因辐合线结构垂直剖面陡峭,在长江流域因低涡环流,形成干冷和暖湿气团的层次叠加混合。在梅雨锋北侧,干冷空气从对流层中高层向下侵入,在淮河流域位置较长江流域偏高且狭窄。湿位涡垂直分布显示,暴雨区与湿位涡斜压项大于0的正涡度发展区对应。干冷动量中心的下传与湿位涡斜压项小于0对应,下传时向南移,其前缘对暴雨雨带位置有指示性;其南下速度,因纬度与密度差异,在淮河流域移速小于长江流域。

英文摘要：

A statistical analysis is done for Meiyu heavy rainfall over Changjiang-Huaihe valleys during2007—2011 based on the daily precipitation data. It has been verified that there are two separate heavy rainfall regions over Changjiang and Huaihe valleys according to the rainfall frequency and distribution during Meiyu season. The two rainfall regions have their different features at prevailing meso-system,spacestructure,Meiyu front location,moisture transportation channel,rainstorm position,dry and cold air intrusion,southward movement of dry-cold momentum,etc. Under dominated dynamic circulations at high level,more low vortex heavy rainfall（ 77%） happened over Changjiang valley and more convergence line heavy rainfall（ 86%） happened over Huaihe valley. The prevailing shallow meso-systems cause the characteristics of Meiyu heavy rainfall with strong rainfall and weak wind. The low vortex over Changjiang valley brings moisture from both South Sea and East Sea,so it makes the heavy rainfall with a larger and wider covering area in Changjiang valley than that in Hauaihe valley. The convergence line in Hauaihe valley brings moisture from only South Sea. The dense zone of the potential pseudo-equivalent temperature isoline presents the Meiyu front and the leading edge of the dry and cold air,with an abrupt shape for the convergence line structure in Huaihe valley but a dry and moisture overlapped shape for the low vortex structure in Changjiang valley. On the north side of Meiyu front,the dry-cold intrusions from mid-high troposphere are downward,with a lower center position and a larger size in Changjiang valley than in Huaihe valley. The vertical distribution of moist potential vorticity shows that the heavy rainfall area is under the baroclinic part of moisture potential vorticity more than 0,a positive vorticity development area. The dry and cold momentum is presented by the baroclinic part of moisture potential vorticity less than 0,its centre transports downward and southward,and its south edge has indicati