李兆慧,王东海,麦雪湖,吴凯露,刘英,王红艳,朱建军,炎利军,李彩玲,陈慧娴,龙妍妍. 2017. 2015年10月4日佛山龙卷过程的观测分析[J]. 气象学报, 75(2):288-313, doi:10.11676/qxxb2017.013
2015年10月4日佛山龙卷过程的观测分析
Observations of the tornado occurred at Foshan on 4 October 2015
投稿时间:2016-06-25  修订日期:2016-11-22
DOI:10.11676/qxxb2017.013
中文关键词:  强龙卷风  灾情调研  钩状回波  佛山
英文关键词:Severe tornado  Damage survey  Hook echo  Foshan
基金项目:广东省气象局科学技术研究项目(2014B21)和佛山市气象局科学技术研究项目(201307)。
作者单位E-mail
李兆慧 佛山市气象局 佛山市龙卷风研究中心, 佛山, 528000  
王东海 中山大学大气科学学院, 广州, 510275
中国气象科学研究院灾害天气国家重点实验室, 北京, 100081 
wangdh@cams.cma.gov.cn 
麦雪湖 佛山市气象局 佛山市龙卷风研究中心, 佛山, 528000  
吴凯露 佛山市气象局 佛山市龙卷风研究中心, 佛山, 528000  
刘英 中国气象科学研究院灾害天气国家重点实验室, 北京, 100081  
王红艳 中国气象科学研究院灾害天气国家重点实验室, 北京, 100081  
朱建军 佛山市气象局 佛山市龙卷风研究中心, 佛山, 528000  
炎利军 佛山市气象局 佛山市龙卷风研究中心, 佛山, 528000  
李彩玲 佛山市气象局 佛山市龙卷风研究中心, 佛山, 528000  
陈慧娴 佛山市气象局 佛山市龙卷风研究中心, 佛山, 528000  
龙妍妍 中国民用航空飞行学院, 广汉, 618307  
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中文摘要:
      受1522号台风彩虹外围螺旋云带影响,2015年10月4日15时28分—16时(北京时)广东佛山出现了EF3级强龙卷并造成严重灾害。为了综合分析龙卷发生的多尺度环境背景场和龙卷的结构及强度变化等特点,进行了灾情调研,航拍龙卷灾情路径,走访龙卷目击者,确认龙卷路径及灾情级别,再结合多渠道获取的龙卷视频照片等资料以及观测资料进行分析研究,结果表明:(1)产生此次龙卷的超级单体存在于台风彩虹外围螺旋云带内;龙卷向西北偏北方向移动,触地时长为32 min,受灾路径长度为31.7 km,最大受灾直径为577 m,平均速度约为60 km/h,具有“移动速度快,影响范围广,破坏力强”的特点,其移动速度快慢似与超级单体强度和地面的粗糙度有关。(2)佛山地区中高层受偏南气流控制,水汽充足,地面有弱冷空气;珠三角喇叭口地形有利于气流的辐合与局地涡旋的产生; 抬升凝结高度低,风垂直切变大,有利于龙卷的生成。(3)地面自动气象站气象要素表现出受龙卷环流影响的特征。3 s极大风速的大值带和3 s最低气压的低值带以及1 h累计降水大值中心呈现出与龙卷走向一致的东南—西北向带状分布;龙卷到来时其周围自动气象站气温和气压明显降低,风速明显增大,风向明显改变;降水在龙卷靠近前5—10 分钟就开始明显增大,其大值中心位于龙卷路径的西侧。龙卷离开后气压比龙卷来临前有所升高,但气温较前降低。(4)龙卷出现在钩状回波前进方向的右后侧;降水大值区与雷达组合反射率大值区基本一致。地面风场的辐合中心与龙卷触地的位置基本一致,并且钩状回波的入流区与地面偏东风区相对应。龙卷风暴单体发展高度在4 km左右,具有低重心对流的特点。其前部存在回波悬垂,一条很窄的向西北倾斜的回波大值带可能与龙卷漏斗云墙有关。对应径向速度剖面图上为一条向西北倾斜的正、负速度交界区,构成一个逆时针旋转的涡旋带,切向剖面图上存在较强的辐合。(5)龙卷发展过程中伴随着龙卷风暴顶和风暴底的逐渐下降以及单体质心的下降,中气旋与龙卷涡旋特征的顶和底也随之逐渐下降。龙卷风涡旋特征的顶高和底高都略低于中气旋,并在龙卷触地时降至最低。龙卷涡旋的切变值远大于中气旋的切变值,且在龙卷强度最强时最大。
英文摘要:
      A tornado, rated as a category 3 storm on the enhanced Fujita scale (EF3), occurred at Foshan as part of Typhoon "Mujigae" (2015) between 15:28 BT and 16:00 BT 4 October 2015. This tornado lasted for 32 min and destroyed a large number of factories and houses. The tornado swath was about 31.7 km, and the largest tornado swath diameter reached up to 577 m. Photos and tornado videos were collected in the survey of damages caused by the tornado. In addition, the surface automatic weather station data, regular observational data, and Doppler radar data were used in this paper to analyze this tornado process. The tornado life cycle was divided into three stages:The developing stage, the mature stage, and the dissipating stage. The tornado moved faster in the developing and mature stage than in the dissipating stage when it slowed down due to changes in the intensity of the supercell and surface roughness. The large-scale circulation featured by obvious wind shear and high moisture in the lower levels was favorable for the tornado genesis. Cold air extended to the south as the small trough stretched southward in the surface layer, high SWEAT index, high K index and low lifting condensation level (LCL) were found in the unstable layer. These were necessary environmental conditions for tornado genesis. The bell shape terrain of the Pearl River Delta region is also favorable for the development of convergence and local vortex genesis in the surface layer. The variables recorded by the surface automatic weather stations showed strong signals when the tornado passed by. The distribution of 3 s gust and 3 s minimum pressure extended along the northwest-southeast direction, which was consistent with the tornado swath. The pressure and temperature dropped sharply while the wind speed increased dramatically during the tornado development period, and cyclonic convergent winds circled around the tornado. The rainfall started to increase 5 to 10 min before the tornado arrived, and the main rainfall zone was located to the left of the tornado path, indicating that the tornado was situated in the right-rear flank of the supercell. The pressure was higher and temperature was lower after the tornado left than that before the tornado came. The Tornadic Vortex Signature (TVS), the hook echo, and bounded weak echo region were detected when the tornado touched down. The heights of the TVS's top, base and the centroid decreased as the storm strengthened and descended to the lowest level when the tornado touched down on the ground. The wind shear was much higher than that of the detected mesocyclone, which also increased when the tornado touched down.
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