利用济南和烟台多普勒天气雷达资料,结合环境物理量和天气实况,对发生在山东境内的3次非超级单体龙卷风暴进行了分析。结果表明,三次龙卷过程发生在利于雷暴产生的环境形势下。低层湿度大,低层明显的垂直风切变和有利的地形是三次非超级单体龙卷发生的有利条件。三次龙卷都发生在风暴单体发展阶段,风暴顶高和强中心高度在1个体扫时间内迅速增高。上升气流的加强和复杂的地形是诱发小尺度强切变的主因。风暴单体的迅速发展,需要强的上升气流配合,上升气流将水平方向的旋转切变抬升为垂直方向,在复杂地形作用下可产生局部小尺度涡旋运动,诱发小尺度范围的强切变,从而导致龙卷发生。
Three non-supercell tornadic storms in Shandong Province were analyzed based on doppler radar data from Jinan and Yantai in combination with environmental parameters and weather events. The results showed that: The environment situations were conducive for the thunderstorms occurring. The greater humidity in the lower level, the significant 0~1 km vertical wind shear and the favorable topographic played an important role in the occurrence of three non-supercell tornadoes. Three tornadoes formed during the rapidly developing stages of thunderstorms, the storm top and the height of the maximum reflectivity markedly increased by more than 2 km within 6 min, although the maximum reflectivity had no significant changing sometimes. The strong updrafts, quickly building up within storms, and the favorable topographic were the main incentives for the occurring of tornadoes. The strong updraft lifted the horizontally rotating wind shear into a vertical position. This mechanism and favorable topographic effect intensified the small-scale circulation within the updraft, called a small-scale vortex. If this area of circulation intensified enough, the circulation reaches the ground as a tornado.
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