豫西深秋一次典型超级单体风暴的多普勒雷达分析

利用三门峡市多普勒天气雷达资料,分析了2009年10月4日发生在河南渑池县的一次产生冰雹的超级单体风暴的回波结构及演变特征,结果表明:超级单体是在上冷下暖的大尺度环流背景和不稳定层结下产生的;其演变过程经历了生成、发展、成熟、消亡四个阶段;局地生成的弱回波若发展较快,速度场中又有逆风区与之配合,则容易发展成超级单体风暴,应引起高度重视;发展阶段回波强度加速增大,诸如底层钩状回波、有界弱回波区、中气旋等超级单体的典型结构特征开始出现,是发布预警的关键时段,大约可以提前15-30 min;成熟阶段最重要的特征是持续存在的中气旋。超级单体风暴其初始回波出现在4 km左右的中空,具有向上向下迅速发展的特点;最强回波强度大,顶高伸展高;当最强回波底到达地面时意味着冰雹、降水的开始,因而可以通过分析最强回波顶高的演变趋势来确定降雹强弱和时间;VIL可用来判断对流风暴强度,持续高的VIL值可能与超级单体风暴有关。

Doppler Radar Analysis of a Typical Supercell Storm in Late-autumn of Western Henan

Based on the Doppler weather radar data in Sanmenxia city, the structure of echoes and evolution characteristics of a supercell storm produced hail in Mianchi county in October 4th 2009.The results show that: supercell happens in the backgrounds on the large scale circulation with warm down, cool up and unstable stratification; the evolution has formation, development, maturity and disappearance 4 stages; if local weak echo develop more quickly, and adverse wind region in the velocity field coordinated with it, supercell storm can formation easily. When echo intensity accelerated increase in development stage, and typical structural characteristics of supercell like subbing layer hook echoes, BWER, mesocyclone happen, it is key time to publish forewarning, and can be 15-30 min early. At maturity stage, the sustaining mesocyclone is the most important characteristic. The initial echo of supercell storm happens at about 4km high, and develop quickly to upside and downside; the strongest echo value of supercell storm is big, and the top elevation is high; when the base of the strongest echo reach the ground, the hail and precipitation begin, so the strength and time of hail can obtain form the evolution trend of the strongest echo top; VIL can judge the strength of convection storm, and the VIL value keep high may concerned with the supercell storm.