湖北一次大暴雨过程中两个时段强降水资料的对比分析

The Comparative Analysis of Strong Precipitation Data in the Two Heavy Rainfall Times during a Torrential Rain Process in Hubei Province

利用NCEP/NCAR再分析资料、地面加密自动站资料以及FY-2C TBB资料与多普勒雷达回波资料等,对2008年8月28 ～ 30日湖北盛夏一次大暴雨过程中的2个强降水时段进行了对比分析.结果表明,此次大暴雨过程主要发生在夜间至清晨,有2个降水明显增强的时段,第2阶段的平均降水强度和极值降水强度更大;第1时段强降水是由暖切变与中低层暖湿气流影响造成,第2时段强降水主要是由东北冷气流和深厚的西南暖湿气流交汇,在中低层形成冷切,且伴随着副高北抬加强,制约切变线停滞少动,不断触发着对流的产生,形成强降水;强降水时段内中尺度环境场特征有利于降水的发生,但第2时段各物理量比第1时段强,因此造成的降水强度更大;雨团与云团的活动规律基本一致,中尺度对流复合体与此次暴雨过程关系密切;镶嵌在回波带中的对流回波单体与强降水的落区有较好的对应关系,且夜晚至凌晨时段是对流单体发展的活跃期,往往能发展至最旺盛阶段且有明显的“列车效应”;但第2时段中尺度对流系统相对第1时段组织结构更有序、生命史也更长.

Using NCEP/NCAR daily reanalysis data, available intensive observations data, FY2C TBB and Doppler radar echo data, the com- parative analysis about the two heavy rainfall times during a torrential rain process in I-Iubei Province from August 28 to 30 in 2008 was conducted The results show that the rainstorm occurred mainly during the night and early in the morning. There were two significantly precipitation enhance- ment time during the torrential rain process, the second stage had more obvious average intensity of precipitation and extreme precipitation inten- sity. The vortex shear and the low layer of warm air were affected by the first one, the Northeast air flow and the deep southwest warm wet air were current intersection, IT caused the formation of cold shear in the lower. The accompanied by the northward movement of subtropical high strengthening restricted the shear line stagnant affected the second one. The characteristics of environmental field scales were advantageous to the precipitation. The hourly rainfall and cloud characteristics of the two stage indicated that, they have the same movable regulation, the enhance- ment stage appeared in the night and early morning. It had a good relationship in the drop zone and precipitation convective echo in echo mono- mer. The night to early morning hours was the convective cells developing active period. They often can develop to the exuberant stage and has the obvious effect of “train”. The second period of mesoscale convective system relative to the first period of organizational structure was more or- derly, longer life history.