A Case Study of Cloud-to-Ground Lightning Activities in Hailstorms under Cold Eddy Synoptic Situation

在山东省有三下得很大的冰雹，在 2002 年 6 月 1 日由一种一样的东北寒冷旋涡状况引起了。发生在天气事件的 Cloud-to-ground (CG ) 闪光被山东闪电察觉网络(SLDN ) 观察，它由在整个山东省盖住的 10 个传感器组成。CG 闪电的时间、空间的分布被从 SLDN， Doppler 雷达和卫星使用数据为三下得很大的冰雹调查。结果证明不同雷雨介绍不同闪电特征就算在一样的摘要的状况下面。积极 CG 闪电的百分比在冰雹掉落的时期期间很高。CG 闪光主要与比 -50

There were three hailstorms in Shandong Province, caused by a same northeast cold eddy situation on 1 June 2002. Cloud-to-ground （CG） flashes occurring in the weather event were observed by Shandong Lightning Detection Network （SLDN）, which consists of 10 sensors covering all over Shandong Province. The temporal and spatial distributions of CG lightning are investigated for the three hailstorms by using the data from SLDN, Doppler radar and satellite. The results show that different thunderstorms present different lightning features even if under the same synoptic situation. The percentage of positive CG lightning is very high during the period of hail falling. CG flashes mainly occurred in the region with a cloud top brightness temperature lower than -50℃. Negative CG flashes usually clustered in the lower temperature region and tended to occur in the region with maximum temperature gradient, while the positive ones usually spread discretely. Negative CG flashes usually occurred in intense echo regions with reflectivity greater than 50 dBz, while the positive CG flashes often occurred in weak and stable echo regions （10-30 dBz） or cloud anvils, although they can be observed in strong convective regions sometimes. Almost all haft falling took place in the stage with active positive flashes, and the peak positive flash rate is a little prior to the hail events. The thunderstorm could lead to disastrous weather when positive CG lightning activities occur in cluster. Severe thunderstorms sometimes present a low flash rate at its vigorous stage, which is probably caused by the ＂mechanism of chargeregion lift＂ through investigating the reflectivity evolution. Combined with the total lightning （intracloud and CG） data obtained by LIS onboard TRMM, the phenomenon of high ratio of intracloud flash to CG flash in severe hailstorm has been discussed. The competition of the same charge sources between different lightning types can also be helpful for explaining the cause of low CG lightning activities in severe storms.