台风龙卷的环境背景和雷达回波结构分析  

Analysis of Typhoon-Tornado Weather Background and Radar Echo Structure

作　　者：郑媛媛[1,2] 张备[1,2] 王啸华[3] 孙康远[1,2] 慕瑞琪 夏文梅[1,2] 

机构地区：[1]中国气象局交通气象重点开放实验室,南京210008 [2]江苏省气象科学研究所,南京210008 [3]江苏省气象台,南京210008 [4]徐州市气象局,徐州221002

出　　处：《气象》2015年第8期942-952,共11页Meteorological Monthly

基　　金：国家自然科学基金项目(41475042和41175043);公益性行业(气象)科研专项(GYHY201306008和GYHY201506006);江苏省气象科研重点项目(KZ201407);江苏省科技支撑计划-社会发展项目(BE2013730和BE2015731);北极阁基金(BJG201302);中国强对流预报专家团队共同资助

摘　　要：利用NCEP再分析资料、常规观测和地面加密观测资料及多普勒雷达资料,对10次台风龙卷过程的环境背景和其中F2~F3级以上龙卷过程的回波结构演变特征进行了详细分析,主要结果如下:(1)台风龙卷所处环境基本为弱对流有效位能(200~1000 J·kg^(-1))和风随高度强烈顺转的强低空风的垂直切变环境,0~1 km风的垂直切变超过10^(-2)s^(-1),风暴的相对螺旋度很大,台前龙卷环境的粗理查孙数很小,平均在40以下。台风龙卷大多数出现在台风前进方向的东北侧,位于0~1km风切变和相对风暴螺旋度大值区。龙卷主要产生于台风外围螺旋雨带上,台前龙卷往往产生前地面已存在风向切变和风速的辐合,但温度梯度不大。(2)在台风影响环境下导致龙卷的风暴属于微超级单体风暴,有水平尺度2~4 km的中气旋;垂直涡度限制在4 km以下;风暴单体的质心在2 km左右,风暴伸展高度在5~7 km。Based on NCEP reanalysis data,conventional observations data,surface dense observation data and Doppler radar data,the environmental background of 10 tornadoes which occurred within spiral rain belt of typhoon and the evolution characteristics of echo structure of the tornadoes in F2 class and above were studied in detail.The results show that,firsthy typhoon-tornadoes occur in an environment with the weak convective available potential energy（200～1000 J·kg^-1） and strong low-level vertical wind shear where the vertical wind shear between 0 and 1 km more than 10^-2s^-1.The storm relative helicity is very great and the typhoon tornado environment average bulk Richardson number is small,averagely below 40.Typhoon-tornadoes mostly occur on the right sides of the moving-paths of the typhoons where the 0 — 1 km vertical wind shear and storm relative helicity are greater.Typhoon-tornadoes are mainly generated in the spiral rainbands in the outside-region of the typhoons.Before tornadoes come into being the convergence of wind direction and speed appears near the surface,but the temperature gradient is small.Secondly,the storms which produce typhoon-tornadoes are mini supercell storms,with cell centroid being about 2 km and stretching height about 5 — 7 km,accompanying the mesocyclones in horizontal scales about 2 — 4 km.The positive vertical vorticity is limited to below 4 km.

关 键 词：台风龙卷 天气背景 雷达回波特征 

分 类 号：P445[天文地球—大气科学及气象学] P412