天津地区一次局地大暴雨过程MCS传播发展机制

Dissemination and Development Mechanism of MCS During a Heavy Rainstorm in Tianjin

选取2017年8月8—9日天津地区一次局地大暴雨天气过程,着重应用卫星云图、多普勒天气雷达、风廓线组网资料深入分析,结果表明:本次局地暴雨由两个MCS产生,对应有A、B两个中尺度雨团,A雨团持续了4 h,雨强相对较大,B雨团持续了3 h,雨强相对较小。强降水发生在TBB低值中心偏向温度梯度最大的区域。两个雨团对应的降水回波移动路径和强度特征存在差异,A雨团回波自西北向东南方向移动,为高质心带状降水回波;B雨团回波自西南向东北方向移动,为低质心带状回波。高质心降水回波雨强高于低质心降水回波。风廓线雷达资料有助于分析中尺度对流系统的移动方向,A雨团为上冷下暖的高低空配置,B雨团降水出现在整层西南气流中,由于环境场的差异导致回波的移动方向和天气剧烈程度的不同。

For the heavy rainfall case occurring from 8 to 9 August 2017,satellite,Doppler radar,and wind profile data were used to study this heavy rainfall.The results showed that the storm should have two MCS.The two mesoscale rain mass A and B affected Tianjin.The rain mass A lasted for 4 hours and the rain intensity was larger.The rain mass B lasted 3 hours and the rain intensity was smaller;The heavy precipitation occurred in the region with the highest temperature gradient in the center of the low value of TBB;There were differences in the moving path and intensity characteristics of echoes.The echo A was a band-shaped high echo and moving from northwest to southeast;the echo B moving from southwest to northeast,it was the low band echo.The echo intensity of high-center precipitation is higher than that of low-center precipitation.The wind profile data helps us to analyze the movement direction of the mesoscale convection system.The rain mass A was a high and low altitude configuration with upper and lower temperatures.The rain mass B precipitation appears in the entire southwest air flow.The difference of the environment results in the difference of the moving direction of the echo and the intensity of the weather.