摘要
2012年4月开汛后广东省接连出现强对流天气,尤其是冰雹日数更是超过历史同期平均。本文利用常规天气观测资料和雷达、自动站等非常规资料对广东首次观测到的风暴分裂中左移超级单体风暴和飑线内超级单体风暴引发的两次强对流天气过程进行了对比分析。结果表明:"4·10"冰雹和雷雨大风天气是由局地强烈加热产生的"热雷暴"发展成超级单体风暴造成的;"4·12"冰雹、雷雨大风和短时强降水天气由飑线及飑线内超级单体风暴造成的,其产生于切变线、较强冷空气南下过程中的低层暖平流和中层冷槽共同作用的环境条件下,较强的平流过程使垂直风切变明显增大;两次过程中0℃层高度都低于4月当地0℃层高度平均值。风切变矢量随高度的变化决定了左移和右移风暴的发展趋势,"4.10"风切变矢量随高度逆时针变化,使风暴分裂后左移风暴得以发展成超级单体;"4·12"风切变矢量随高度顺时针变化,有利于有组织风暴即飑线和飑线内超级单体的形成和发展,超级单体向承载层平均风的右侧运动。左移超级单体回波具有中反气旋、弱回波区和旁瓣回波及强回波中心位于其移动方向左侧等特点;飑线内超级单体的中气旋、弱回波区和强回波中心位于回波移动方向右侧,三体散射长钉长度和中层辐合厚度都很大,后侧下击暴流产生了31.1 m·s^(-1)地面强风。
In April 2012,a series of severe thunderstorms which produced more hails than normal were seen in the Guangdong Province.This paper analyses two severe convective weather events,which are one left-moving supercell in the splitting storm that was observed first time in Guangdong and one supercell in a squall line,by using conventional meteorological observations,Doppler radar data and surface automatic weather station observations.The results show that a “thermal thunderstorm”initiated by local intense heating developed into a supercell storm which produced hails and severe wind gusts on 10 April.On 12 April,one squll line and the supercell which brought hails,severe wind gusts and torrential rains in a very short time were developed by the role of low-level warm advection and middle-level cold trough in the process of a shear line and a strong cold front moving southeastward,while the vertical wind shears went up by the advection process.The 0℃layer heights for the two events were lower than the local mean value in April.It was found that the changing of wind shear vector with heights determined the development trend of left-moving and righ-moving storm:The counterclockwise changing with heights of wind shear vector initiated a left-moving storm developed to a hailstorm after storms splitting on 10 April;and the clockwise changing was conducive for a squall line to be well organized and developed,and the supercell in the squall line moved to the right of the mean wind of the bearing layer.The left-moving supercell was characterized by a anti-mesocyclone,WER,side-lobe echoes and a strong echo center on the left side.The supercell in the squall line featured a mesocyclone,WER,side-lobe echoes and a strong echo center on the right side,the long TBSS and massive mid-level convergence,with 31.1 m·s-1 backside downburst.
出处
《气象》
CSCD
北大核心
2014年第6期655-667,共13页
Meteorological Monthly
基金
广东省科技计划项目(2011A030200015)
中国气象局关键技术集成及应用项目(CMAGJ2014M39)
公益性行业(气象)科研专项(GYHY201406002和GYHY201406009)
广东省气象局科技创新团队-2共同资助
关键词
风暴分裂
左移超级单体
飑线
冰雹
splitting storm
left-moving supercell
squall line
hail
