1522号“彩虹”台风龙卷现场调查与中尺度特征分析

Damage survey and mesoscale features analysis on tornado in outer rain-band of typhoon “Mujigae” on 4 October 2015

2015年10月4日,当年第22号台风"彩虹"外围螺旋雨带中发生两次龙卷天气,分别袭击了广东省佛山市顺德区和广州市番禺区。通过现场灾情调查、互联网视频和照片、新一代天气雷达观测等资料的综合分析,确定这两次龙卷最大强度达到EF3级。分析了典型台风龙卷的发生发展过程及其致灾和中小尺度特征。主要结论如下:两次龙卷过程发生的环境条件是,龙卷位于"彩虹"台风右前象限,地面存在触发对流的中尺度辐合线,水汽充沛,抬升凝结高度低,0—1 km垂直风切变强;天气雷达资料分析表明,顺德龙卷出现在勾状回波顶端、中气旋持续时间约1 h,番禺龙卷出现在弓型回波断裂处,中气旋持续时间约40 min;两次龙卷过程在迅速发展阶段都表现出中气旋尺度缩小、高度下降、径向切变增强等特征。上述结论可作为我国台风龙卷业务监测和预警的参考依据。

In the spiral rain-band at the periphery of typhoon“Mujigae”（No.1522）, two tornado events occurred on 4 October 2015, and stroke Shunde district, Foshan city and Panyu district, Guangzhou city, Guangdong province, respectively. According to the synergetic analysis of damage survey, network videos and photos, and Doppler weather radar data and so on, the highest intensity of two tornado events is determined to reach EF3 level. We have analyzed the formation and development, damage and meso- and micro-scale features of two typical tornado events with typhoon. Two tornado events occur in the following environment conditions. The tornadoes are located in the right forward quadrant of typhoon“Mujigae”. There are mesoscale convergence lines triggered convection in the surface. Water vapor is rich, LCL level is lower, and 0-1km vertical wind shear is strong. Analysis of weather radar data shows that the tornado occurred in Shunde emerges at the apex of hook-shaped echo and the duration of mesocyclone is about 1 hour, while the tornado occurred in Panyu emerges at the break place of bow-shaped echo and the duration of mesocyclone is about 40 minutes. It is shown that mesocyclone scale reduces and its height descends,and radial wind shear strengthens during the period of rapid development of two tornado events. These aforementioned conclusions can be used operationally as the reference in the monitoring and early warning of tornado with Typhoon in China.