1522号台风外围强龙卷CINRAD/SA气象产品特征研究
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摘要
利用新一代天气雷达CINRAD/SA雷达系统的探测资料和气象产品,分析了2015年10月4日发生在广东佛山台风外围强龙卷的特征。龙卷发生在距离台风中心约350 km雨带中的小型超级单体中,风暴单体的回波顶发展到12 km左右。龙卷发生前,大于50 d BZ的强反射率因子核发展到5.5 km;龙卷发生后,强中心高度下降,强反射率因子核的高度降低到3.5 km。风暴单体的低层后方出现钩状回波,钩状回波的末端出现高达65 d BZ的强反射率因子。风暴单体的中气旋发展高度低,延伸厚度浅薄,切变强烈。无辐合辐散的纯气旋性环流层的高度在1.2 km左右,其下方是辐合气旋性流场,上方是辐散气旋性流场。与经典超级单体中的中气旋相比,就如垂直方向上压缩了的中气旋。中气旋下方,低层辐合的强弱,与龙卷的强弱变化密切相关,在龙卷发展到最强之前,低层辐合很强,随着低层辐合的减弱,龙卷也随之减弱。中气旋适配参数的阈值用雷达系统的缺省值时,第一次算出中气旋的时间比龙卷出现的时间提前16 min,而适当降低阈值后,算出第一个中气旋的时间比龙卷出现的时间提前了58 min。雷达系统输出第一个龙卷涡旋特征(TVS)产品比实际龙卷发生的时间提前了4 min。因为距离雷达很近,在1536(北京时,HHMM,下同)和1542时次,雷达探测到了表征龙卷碎片特征(TDS)的高反射率因子。
Using the observation data and meteorological products of CINRAD/SA Radar system,the characteristics of the violent tornado occurred in Guangdong Province on 4 October 2015 were analysed. The significant tornado was spawned from a minisupercell located in the out rainband of Typhoon Mujigae. The storm top reached about 12 km. The intensity core of 50 dBZ is about 5.5 km before tornado touches down,It descends to 3.3 km after tornado happens. The low level reflectivity exhibits classic hook echo with 65 dBZ high reflectivity at the end of the hook. The low altitude mesocyclone has high shear. Non divergence level was located at about 1.2 km,with convergencecyclone below and divergence cyclone above.Liken to the mesocyclone in supercell,it has been constringent in vertical direction. Strength of the tornado is relative to the convergence intensity under the mesocyclone. The first time the mesocyclone product been given out was 16 min ahead of tornado happens,when the threshold of the adaptation parameter using the default value of the algorithm.Adjust the adaptation parameter to a resonable lower value,the first time the mesocyclone been given out was58 min ahead of tornado happens. The first Tornado Vortex Signature( TVS) products been given out by radar system was 4 min ahead of time the actual tornado occurrence.Because it's close to radar site,the high reflectivity of Tornado Debris Signature( TDS) was detected at scan of 1536 and 1542.
Using the observation data and meteorological products of CINRAD/SA Radar system,the characteristics of the violent tornado occurred in Guangdong Province on 4 October 2015 were analysed. The significant tornado was spawned from a minisupercell located in the out rainband of Typhoon Mujigae. The storm top reached about 12 km. The intensity core of 50 dBZ is about 5.5 km before tornado touches down,It descends to 3.3 km after tornado happens. The low level reflectivity exhibits classic hook echo with 65 dBZ high reflectivity at the end of the hook. The low altitude mesocyclone has high shear. Non divergence level was located at about 1.2 km,with convergencecyclone below and divergence cyclone above.Liken to the mesocyclone in supercell,it has been constringent in vertical direction. Strength of the tornado is relative to the convergence intensity under the mesocyclone. The first time the mesocyclone product been given out was 16 min ahead of tornado happens,when the threshold of the adaptation parameter using the default value of the algorithm.Adjust the adaptation parameter to a resonable lower value,the first time the mesocyclone been given out was58 min ahead of tornado happens. The first Tornado Vortex Signature( TVS) products been given out by radar system was 4 min ahead of time the actual tornado occurrence.Because it's close to radar site,the high reflectivity of Tornado Debris Signature( TDS) was detected at scan of 1536 and 1542.
引文
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[2]刘黎平,吴林林,吴翀,等.X波段相控阵天气雷达对流过程观测外场试验及初步结果分析[J].大气科学,2014,38(6):1079-1094.
[3]李兆慧,王东海,麦雪湖,等.2015年10月4日佛山龙卷过程的观测分析[J],气象学报,2017,75(2):288-313.
[4]朱文剑,盛杰,郑永光,等.1522号“彩虹”台风龙卷现场调查与中尺度特征分析[J].暴雨灾害,2016,35(5):403-414.
[5]李彩玲,炎利军,李兆慧,等.1522号台风“彩虹”外围佛山强龙卷特征分析[J].热带气象学报,2016,32(3):416-424.
[6] Zhao K,Wang M,Xue M,et al. Doppler Radar Analysis of a Tornadic Miniature Supercell during the Landfall of Typhoon Mujigae(2015)in South China[J]. Bulletin of the American Meteorological Society,2017,98(9):1821-1831.
[7] Xue M,Zhao K,Wang M,et al. Recent Significant Tornadoes in China[J].大气科学进展,2016,33(11):1209-1217.
[8]麦雪湖,炎利军,李兆慧.2015年10月4日佛山强龙卷风灾害过程浅析[J].广东气象,2015,37(6):6-8.
[9]周后福,刁秀广,夏文梅,等.江淮地区龙卷超级单体风暴及其环境参数分析[J].气象学报,2014,72(2):306-317.
[10]郑媛媛,张备,王啸华,等.台风龙卷的环境背景和雷达回波结构分析[J].气象,2015,41(8):942-952.
[11] Dowell D C,Bluestein H B. The 8 June 1995McLean,Texas,Storm. Part II:Cyclic Tornado Formation,Maintenance,and Dissipation[J].Monthly Weather Review,2010,130(11):2649-2670.
[12] Ryzhkov A V,Burgess D W.Zrni'c D S,et al.Polarimetric analysis of a 3 May 1999 tornado[C].In 21th Conference on Severe Local Storms,San Antonio,TX. Boston:American Meteorological Society(Preprints),2002.