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珠江三角洲台风龙卷的活动特征及环境条件分析
(1.广东省佛山市气象局;2.佛山市龙卷风研究中心;3.中国气象局气象干部培训学院)
Analysis of Typhoon-Tornado Activity Characteristics and Environmental Condition in the Pearl River Delta
(1.Foshan Meteorological Service;2.Foshan Tornado Research Center;3.China Meteorological Administration Training Center)
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投稿时间:2018-04-16    修订日期:2019-01-14
中文摘要: 利用常规观测、区域自动气象站、多普勒天气雷达等资料分析珠江三角洲台风龙卷的时空分布特征及其产生的环境条件。结果表明:(1)珠江三角洲台风龙卷具有较强的地域性,以佛山最为高发;龙卷出现在6到10月热带气旋活跃期,8月份最为多发,对应热带气旋在华南西部登陆的高峰期;龙卷发生起始时间多集中在北京时间(下同)10—20时。(2)珠江三角洲台风龙卷发生在台风登陆后1.3—21.3h的时段内,其中82%发生在台风登陆后9—15h;龙卷多数出现在登陆台风中心的东北象限,台风中心位于广东湛江—广西东南部或北部湾一带时是珠江三角洲台风龙卷发生的高风险时段。(3)高层辐散、低层辐合及中低空强东南急流在珠江口附近上下叠加是珠江三角洲强或弱台风龙卷产生的有利大尺度环流背景,但强龙卷过程的东南急流特别是低空的东南急流更强。(4)珠江三角洲强或弱台风龙卷环境条件的共同特征表现为不大的对流有效位能(CAPE)、低抬升凝结高度(LCL)和较强的深层和低层垂直风切变及较大的风暴相对螺旋度(SRH),强和弱龙卷对应的环境条件的主要差异在于前者的深层和低层垂直风切变和风暴相对螺旋度SRH更大;相似台风路径下,珠江三角洲有/无台风龙卷环境条件的明显差异在于0~1km的低层垂直风切变和SRH,0~1 km垂直风切变和SRH越大,出现超级单体或中气旋的可能性越大,产生龙卷的可能性也就越大;地面辐合线和地面小尺度涡旋是有利于台风龙卷触发和发展的重要中小尺度天气系统。(5)台风龙卷风暴母体具有低层钩状回波及其与暖湿气流相连接的入流缺口回波等经典超级单体风暴的部分特征,属于低质心的微型超级单体风暴;在新一代天气雷达径向速度图上低层可探测到强中气旋或中等强度的中气旋,有时强中气旋中心还伴有明显的TVS;龙卷多数出现在钩状回波顶端或TVS附近。与西风带超级单体龙卷相比,台风龙卷中气旋的尺度更小、垂直伸展高度更低。
Abstract:Based on the data of conventional observation, automatic weather station (AWS) observation, Doppler weather radar, this paper analyzes the characteristics of spatial-temporal distribution and environmental condition on the Typhoon-tornadoes in the Pearl River Delta. The results show that tornadoes have a strong regional feature with higher frequency in Foshan city. Tornadoes occur during the active period of tropical cyclones from June to October,August is the peak with corresponding to the peak of landfalling tropical cyclones in the west of South China. The peak frequency of tornadogenesis in the diurnal variation is from 10:00 to 20:00 BT.Tornadoes occur between 1.3h and 21.3h after landfall, about 82% of the tornado record occurs from 9h to 15h after landfall. A strong preference for tornado occurrence is in the northeast quadrant with respect to land-falling typhoon center,the high risk periods of tornadogenesis in the Pearl River Delta correspond to the typhoon center locating between Zhangjiang Guangdong and southeast Guangxi or Beibu Gulf. The synoptic situation of upper-level divergence, low-level convergence, and superimposition of strong southeasterly jet at mid- and low-layer over the Pearl River Delta are conducive to the weather background of weak or strong tornado events, but strong tornado events have stronger southeast jet at low-level. The common environmental conditions for strong or weak tornadogenesis appear to be weak CAPE, low LCL, strong deep-layer and low-level vertical wind shear(VWS) and high storm relative helicity (SRH). The major difference between weak and strong tornado cases is that the latter has stronger deep-layer and low-level VWS and greater SRH. The significant diversities are VWS at 0~1 km and SRH between tornadic and nontornadic environmental conditions under the similar typhoon tracks. With the higher value of VWS and SRH, the possibility of supercells and mesocyclones increases, tornadoes are most likely to be detected. Surface convergence line and small-scale vortices are conducive to the typhoon tornadogenesis. Tornado storms are mini supercell storms with low centriod and have some typical features, such as hook echo in low level and Fin echo connected to warm and wet air. Strong or moderate mesocyclones are likely to be detected through the radial velocity data of the CINRAD/SA radar at low level, significant TVS may be found at the center of mesocyclones. The tornadoes locate in the interior of the hook echo or near TVS. Comparing typhoon tornadoes with Westerly supercell tornadoes, mesocyclones of typhoon tornadoes are smaller in scale and lower in stretching height.
文章编号:201804160173     中图分类号:    文献标志码:
基金项目:(41175043和41675023)和广东省气象局科技项目(2016B39)共同资助第一作者:黄先香,主要从事强对流天气预警研究.Email:fsqxj@163.com通信作者:俞小鼎,主要从事强对流天气的多普勒天气雷达探测和预警以及临近天气预报研究.Email:xdyu1962@126.com
引用文本:
黄先香,俞小鼎,炎利军,李彩玲,李兆明,0.[en_title][J].Meteor Mon,():-.
HUANG Xianxiang,YU Xiaoding,YAN Lijun,LI Cailing,LI Zhaoming,0.Analysis of Typhoon-Tornado Activity Characteristics and Environmental Condition in the Pearl River Delta[J].Meteor Mon,():-.