Abstract: Two rare torrential rain processes occurred in north He’nan Province on July 9 and 19, 2016, which caused severe effect and property losses on the life of people and various industries. Based on precipitation data from automatic weather stations, radar composite reflectivity and base reflectivity, conventional radiosonde and surface observation data and reanalysis data from European Centre for Medium-Range Weather Forecasts (ERA-Interim), the precipitation characteristics, extremity of water vapor and dynamic conditions, relation between topography and precipitation and characteristic of mesoscale convective system were analyzed. Results show that: (1) There was large daily rainfall that created new history record of daily rainfall during the two torrential rain processes, and strong convection characteristics were quite obvious. The heavy rainfall centers were both on the east of the Taihang Mountains, while the influence systems and rainfall range were different. (2) There were two water vapor transports from southwest and southeast from tropics and subtropics, and the total water vapor conditions were good during the two rainfall processes. The total precipitable water of “7.09” rainstorm was obviously extreme, while the vapor condition of “7.19” rainstorm was close to the average value during heavy rainfall processes at the same period and the extremity was not obvious. (3) The dynamic conditions of two torrential rains were quite different. The dynamic condition of “7.09” rainstorm was weak, and the 700 hPa vertical velocity over Xinxiang station (the heavy rainfall center) was much lower than the multi-year average value during heavy rainfall processes in July. For” 7.19” rainstorm, the 700 hPa vertical velocity over Linzhou station (the heavy rainfall center) was 3 times of the multi-year average value during the 28 heavy rainfall processes in July since 1981, which showed that the extremity was quite obvious. (4)The two torrential rain processes were both accompanied by genesis, development and maintenance of surface mesoscale convergence lines, which triggered genesis and merge of the convective units. The enhancement and maintenance of convective units were corresponding to the large hourly rainfall intensity. The convective cloud clusters had the characteristics of low centroid and high efficiency precipitation. (5) The topography of the Taihang Mountains had positive effect on increment of precipitation.

Key words:  torrential rain, extremity of physical quantity, mesoscale characteristic, surface mesoscale convergence line

摘要： 2016年7月9日和19日，河南省北部出现两次罕见特大暴雨过程，给人民生活及各行业造成重大影响和财产损失。利用河南省自动气象站降水量、雷达回波及常规探空、地面观测资料以及欧洲中期天气预报中心1°×1°再分析资料(ERA-Interim)，对这两次过程的降水特点、水汽和动力条件的极端性、地形与降水的关系及中尺度对流系统特征进行诊断分析。结果表明：（1）两次特大暴雨过程具有降水日雨量突破历史极值、强对流特征明显、强降水中心位于太行山东麓迎风坡等共性特征，但二者具有不同的影响系统，降水范围有明显差异；（2）两次特大暴雨过程均存在来自热带和副热带的西南和东南两支水汽输送，整层水汽条件较好，其中“7.09”过程的整层可降水量具有明显极端性，而“7.19”过程中，水汽条件接近同期暴雨过程的平均值，极端性不明显；（3）两次过程的动力条件有较大差异，“7.09” 过程动力条件弱，强降水中心新乡站的700 hPa垂直速度远小于该站暴雨过程中该值的多年平均值，而“7.19”过程林州站700 hPa垂直速度约是1981年以来28次暴雨过程中该站平均值的3倍，具有明显的极端性；（4）两次过程均伴有地面中尺度辐合线生成、发展和维持，地面中尺度辐合线触发对流单体生成、合并，其增强、维持与大的小时雨强相对应，对流云团具有低质心、高效率降水等特征；（5）太行山地形对两次极端暴雨增幅均有正贡献。

关键词: 特大暴雨, 物理量极端性, 中尺度特征, 地面中尺度辐合线