利用2007年8月8~9日陕西中部一次超强雷暴天气的闪电定位资料、天气图、多普勒雷达和卫星云图资料,从动力学、物理学等方面分析了此次强雷电天气产生的主要原因。结果表明:远距离台风外围的低层偏东气流到达陕西中部,增强了低层的水汽和能量,对大暴雨和强雷电天气的产生起到了非常重要的作用;中-α尺度对流云团发展期是产生高密度大强度雷电的主要时段,雷电主要发生在TBB≤-60℃的云区;产生强雷电的雷达回波强度达到50~60 dBz,垂直液态水含量VIL为60~70 kg/m^2,云顶高度达到或超过15~17 km;雷电的产生主要与对流云低层辐合区水汽通量的大小有关:低层辐合区水汽通量比较小时,有利于雷电的产生。
Based on the data of Cloud-to-Ground (CG) lightning, synoptic observation, radar echo, and satellite cloud image and so on, the main cause of one super thunderstorm in central Shaanxi Province on August 8~9, 2007 were summarized by means of dynamic and physical diagnostic analyses. The results showed that lower-level eastern airflow from far-distance typhoon played very important role in producing heavy rainstorm and severe thunderstorm. It provided more water vapor and energy when the lower-level eastern airflow arrived in central Shaanxi Province. The developing period of meso-α scale convective cloud cluster corresponded to the active period of CG lightning. Most of CG lightning flashes occurred in cloud region with TBB≤-60℃. In this super thunderstorm, the strong radar echo was up to 50~60 dBz, VIL up to 60~70 kg/m^2 and cloud top height up to 15~17 km. There was some correlation between CG lightning activity and water vapor flux in low-level convective convergence zone. Less the supplement of water vapor in the tower-level convergence zone was, more favorable CG lightning flashes occur.