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线状对流中EF3级强龙卷的多尺度机理研究
(天津市气象台)
Multi scale mechanism of EF3 tornado in linear convection
Zhang Nan1, Yang Xiao-jun2,1, Lin Xiao-meng1, Wang Yin1
(1.Tianjin Meteorological Observatory,Tianjin;2.Innovative Group of Numerical Forecast of Tianjin Meteorological Bureau,Tianjin,)
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投稿时间:2019-07-11    修订日期:2020-05-28
中文摘要: 本文利用常规观测资料、多普勒雷达资料、风云四号卫星资料、雷达变分同化分析系统(VDRAS)输出的高分辨率分析场资料对2018年8月13日17:30发生在天津静海地区的EF3级强龙卷过程进行分析,结果表明:此次过程为发生在线状对流中的强龙卷,且引发龙卷的对流风暴不具备超级单体风暴典型特征,龙卷形成后,在涡旋不断加强的基础上,旋转中心在不断下降,且TVS的伸展厚度在不断增大。两个线状对流之间新单体的形成发展促使了线状对流的合并,新生对流单体强回波接地时间与龙卷的发生时间有较好的对应关系。在龙卷发生前20分钟 min,分别位于两条边界层辐合线北侧和西侧的偏北风和前方入流的偏东风构成了中低压的辐合旋转流场,当雷暴出流与龙卷发生地的局地风垂直切变中心(在180米 m高度可达90*10-3 s-1)相遇,辐合线上水平分布极不均匀的上升运动迫使水平涡管倾斜,加强了垂直涡度,涡管在垂直方向上被拉伸,根据角动量守恒,旋转加强形成龙卷母体涡旋,因此,发生在线状对流中的强龙卷虽然在对流模态上与超级单体龙卷不同,但龙卷母体涡旋形成的物理机理是一致的。
Abstract:Based on conventional observation data, Doppler radar data, FY-4 satellite data and VDRAS data, the EF3 tornado process in Jinghai area of Tianjin at 17:30 on August 13, 2018 is analyzed. The results show that This process is a strong tornado occurring in linear convection,andthe convective storm causing tornado does not have the typical characteristics of supercell storm. After the formation of the tornado, on the basis of the continuous enhancement of the vortices, the center of rotation is declining, and the extension thickness of TVS is increasing. The formation and development of new convections between two linear convections promotes the merger of linear convection.There is a good correspondence between the grounding time of strong echoes of new convections and the occurrence time of tornadoes. Twenty minutes before the tornado occurs, The northerly wind on the north and west sides of the two convergence line at boundary layers and the easterly wind constitute the convergence and rotation flow field of the mesoscale low pressure.the thunderstorm outflow meets the local vertical shear center (up to 90*10-3s-1 at the height of 180 meters),the uneven upward motion along the convergence line forces the horizontal vortex tube to tilt, forming a vertical vortex tube and being stretched in the vertical direction,according to the law of conservation of angular momentum,the strong tornado parent vortex is caused by the intensification of rotation. Thus, although the convective mode of non-supercell tornado in linear convection is different from that of supercell tornado, the physical mechanism of tornado parent vortex formation is the same.
文章编号:201907110276     中图分类号:    文献标志码:
基金项目:国家自然科学基金(41675046,41575049);天津市自然科学基金青年项目(18JCQNJC09300);中国气象局预报员专项(CMAYBY2020-009,CMAYBY2020-008,CMAYBY2018-005)
引用文本:
张楠,杨晓君,林晓萌,王莹,0.[en_title][J].Meteor Mon,():-.
Zhang Nan,Yang Xiao-jun,Lin Xiao-meng,Wang Yin,0.Multi scale mechanism of EF3 tornado in linear convection[J].Meteor Mon,():-.