雷州半岛一次台风外围龙卷天
Analysis of Typhoon-Tornado Weather Process in Leizhou Peninsula
中文摘要：
2013年11月11日早晨，距离第30号台风海燕中心约350 km的湛江市徐闻县出现了龙卷，强度为EF1级。利用现场灾情调查、常规高空和地面观测、广东省地面自动站观测和湛江S波段多普勒天气雷达数据等，对此次龙卷天气过程进行分析。结果表明，龙卷发生在副热带高压和台风海燕之间的东南急流辐合的环流形势下，环境条件表现为中等强度对流有效位能、低的对流抑制能量和抬升凝结高度、强的0～6 km和0～1 km垂直风切变以及大的低层相对湿度；地面层的中尺度辐合线和小尺度涡旋提前于龙卷出现，龙卷发生在小尺度涡旋附近。龙卷风暴母体的下沉气流导致的地面冷池气温与周围环境的温差约为1～4 ℃，较小的温差有利于龙卷的形成。龙卷风暴母体为低质心的微超级单体，低层具有钩状回波和入流缺口特征，伴有中等到强中气旋和TVS特征，中气旋和TVS伸展高度在2 km以下；龙卷触地前，中气旋强度增大，直径缩小，底高降低，TVS特征较龙卷提前约24 min出现。
中文关键词：
台风龙卷，环境条件，雷达特征，中气旋
KeyWords：
typhoon-tornado, environmental background, radar echo characteristics, mesocyclone
Abstract：
On the morning of November 11, 2013, a tornado occurred in Xuwen County, Zhanjiang City, about 350 km away from the center of Typhoon No.30 “Haiyan”, with the intensity of tornado event was rated EF1. Based on the disaster investigation, conventional observations data, surface automatic weather station, a Zhanjiang S-band Doppler radar and so on, the environmental background and radar echo characteristics of tornado occurrence and development are analyzed. The results show that the tornado was generated southeast jet convergence zone between the subtropical high and typhoon. The atmospheric conditions show that typhoon-tornado occurred in an environment with medium convective available potential energy, weak convective inhibitory energy, low elevation condensation height, strong 0-6 km and 0-1 km vertical wind shear and large low-level relative humidity. The surface mesoscale convergence line and micro vortex occurred before the tornado. The difference between the temperature of the ground cold pool caused by the sinking airflow of the tornado storm and the environment is about 1-4 ℃ and the smaller temperature difference is conducive to the formation of tornado. The convective storm which produced tornado was mini supercell storm with low center of mass, which has the characteristics of hook echo, inflow gap, moderate to strong mesocyclone and TVS in the lower layer. The mesocyclone and TVS have an extension height below 2 km. Before the tornado occurs, the intensity of the mesocyclone increases, the diameter decreases and the base height decreases. The TVS appears about 24 minutes earlier than the tornado.