1522强台风“彩虹”螺旋雨带中衍生龙卷的超级单体演变与机理研究Ⅰ:谱宽和速度

THE EVOLUTION AND MECHANISM OF TORNADIC SUPERCELLS IN THE OUTER RAINBANDS OF STRONG TYPHOON MUJIGAE (1522). PART Ⅰ:SPECTRUM WIDTH AND MESOCYCLONE SPEED

为揭示多普勒雷达速度谱宽资料对1522号台风"彩虹"螺旋雨带中衍生龙卷的超级单体演变规律的指示作用,基于常规观测资料、多普勒雷达资料和ECWMF再分析资料,分析3个衍生龙卷的超级单体速度谱宽和中气旋速度演变特征。研究表明,速度谱宽可提前10～30 min预示强对流风暴的变化。根据速度谱宽σ与湍能耗散率ε的关系分析,提出了谱宽变化与超级单体内中气旋和龙卷发生发展关系的概念模型。当对流单体进入新的发展阶段时,谱宽值加大呈增强状态;当对流单体处于维持稳定阶段时,谱宽值减小则呈减弱状态。衍生汕尾海丰水龙卷的中气旋最大切向速度19.5 m/s,属中等强度中气旋。衍生顺德龙卷和番禺龙卷的中气旋最大切向速度>27 m/s,均属强中气旋。用多普勒雷达中气旋算法识别的中气旋在距离较远(>80 km)和较近(<17 km)距离上有漏报现象,人工纠正有利于更正预报结果,更准确地指导防灾减灾。

Based on the conventional observations data of China,Doppler radar data and reanalysis data of ECWMF,the evolution and mechanism of three supercells that induced tornadoes in the outer rainbands were analyzed during the landing of“Mujigae”,and this is the first part of the spectrum width and speed from radar data.The varieties of spectrum width could give an indication approximately 10-30 minutes earlier than the actual event,and evolutions of mesocyclones and tornadoes in the three supercells,and the relationships between spectrum width and mesocyclones and tornadoes in supercells were discovered based on the relationship between speed width and turbulence dissipation rate.According to the criteria of mesocyclone recognition guidelines,the maximum rotational velocity of the mesocyclone induced waterspout in Shanwei was 19.5 m/s,classified into moderate mesocyclone,and the velocity of the two mesocyclones induced tornadoes in Guangzhou were more than 27 m/s,classified into strong mesocyclone.The mesocyclone automatically detected by Doppler algorithm missed targets on ranges less than 17km and more than 80 km,therefore manual correction is needed to have more accurate results to guide disaster prevention and mitigation.