An Analysis on the Heavy Rainfall over North China from 18 to 20 July 2016

Abstract

使用美国环境预报中心和美国国家大气研究中心(NCEP/NCAR)提供的FNL资料以及中国气象局气象信息中心提供的全国自动站观测降水量资料、CMORPH卫星反演降水资料，对2016年7月18日至20日发生于华北地区的暴雨天气过程(16•7暴雨)进行了研究，结果表明：16•7暴雨过程主要是由于北上的西南低涡和西来的高原低涡在华北上空相互作用，使得华北地区存在一个深厚的华北冷涡；高低空急流的耦合对16•7暴雨的发生起了重要作用，强降水时段暴雨主要位于副热带高空急流出口区和低空急流出口区的叠加处，高空急流入口区右侧所形成的上升的次级环流和低空急流携带着充足的水汽卷入到华北区域冷涡的涡旋运动中，在华北上空所形成的低层暖湿、高层干冷的空气配置，非常有利于华北上空强对流的产生；来自南海和孟加拉湾以及副热带高压南部的三支水汽在华北的聚集，是导致华北7月20日00时的最大峰值降水的主要水汽条件，当到达华北的水汽由单一的副高西部的偏东气流供应时，华北的降水强度开始出现减弱。 Using FNL data provided by NCEP/NCAR, national automatic stations observations of precipitation data provided by Meteorological Information Center of China Meteorological Administration (CMA) and the CMORPH satellite precipitation data, the extreme severe precipitation in North China in 18 - 20 July 2016 (16•7 rainstorm) was analyzed, the results are as follows. 16•7 rainstorm is mainly caused by the deep North China cold vortex formed by the interaction between the northbound southwest vortex and the westbound plateau vortex over North China. The coupling of upper and lower jet streaks played an important role in the occurrence of 16•7 rainstorm, and during heavy rain time, strong precipitation mainly located in the overlay area of exit region of subtropical upper level jet and lower level jet. The rising secondary circulation formed on the right side of the upper level jet entrance area and the lower level jet carry sufficient water vapor into the vortex movement of the North China cold vortex and the configuration of the warm and wet air in the lower layer and the dry and cold air in the upper layer formed over North China is very beneficial to the generation of strong convection over North China. The gathering of three branches of water vapor from the South China Sea, the Bay of Bengal and the southern subtropical high, is the main vapor condition leading to the max peak precipitation in North China at 00:00 on 20, July. When the water vapor reaching North China is supplied only by easterly air to the west of the subtropical high, the precipitation intensity begins to weaken.