2019年8月29日海南儋州台风雨带中夜间龙卷的多源资料分析

为研究台风雨带在夜间发生的龙卷结构与演变,本文针对2019年8月29日凌晨海南儋州在台风“杨柳”的外围螺旋雨带发生的EF2级龙卷,利用micaps资料、海口双偏振天气雷达资料以及FY2G卫星等资料,对儋州龙卷从热力和动力因素分析夜间台风外围雨带龙卷的演变特征。分析表明：台风“杨柳”从28日20时到29日08时明显加强,夜间海南云顶亮温较周围低,云顶的辐射降温及云团合并,促进热力不稳定;夜间台风雨带登陆海南后,受地面摩擦影响,高低层垂直风切变加大,儋州附近山地地形促进了动力抬升。T-logP图上对流指数以及温度层结和湿度层结特征,均使对流加强。海口双偏振雷达回波显示了龙卷的典型特征,经过退速度模糊,凸显了中气旋、TVS和TDS特征,偏振参量Zdr、KdP和CC的特征也揭示了探测中气旋和龙卷的敏感性。研究结果为预警台风雨带中的夜间龙卷提供了参考依据。

Multi-data analysis of night tornadoes of Danzhou typhoon belt in Hainan Province in August 29th,2019

In order to study the structure and evolution of night tornadoes in the typhoon rain belt,take EF2 tornado in Danzhou, Hainan Province in the early morning of August 29, 2019 in the outer spiral rain belt of Typhoon "Yangliu" for example, this paper analyzes thermal and dynamic factors with the data of MICAPS, Haikou dual polarization radar and FY2G satellite. The result shows that the typhoon "Yangliu" strengthened obviously from 20:00 on the 28th to 08:00 on the 29th, the brightness temperature of cloud top in Hainan was lower than that of the surrounding area at night, the radiation cooling of cloud top increased the temperature difference with the ground, and promoted the thermal instability. After typhoon belt landing in Hainan at night, the vertical wind shear increased in the high and low layers, and the effect of the terrain Danzhou increased the dynamic instability because of the ground friction. The convective index and the stratification characteristics of temperature and humidity on the t-logp plot strengthen the convective. The echo of Haikou dual polarization radar shows the typical characteristics of tornado. After the velocity dealiasing, the evolution characteristics of mesocyclone, TVS and TDS are highlighted. The evolution of polarization parameters ZDR, KDP and CC also reveal the sensitivity of detecting mesocyclone and tornado. The results provide the reference for the night tornado in the typhoon rain belt of the early warning platform.