The Relationship Between Lightning Activity And Radar Echo Characteristics Of Thunderstorm

The current research results suggest that there is a close relationship, which is not yet clarified in detail, between lightning activity and thunderstorm's micro-physics and dynamic conditions. Therefore, it is necessary to carry out further research on this relationship. And it is of vital significance for studying of lightning activity and improving the lightning warning and forecast system.The parameterization scheme between lightning activity with thunderstorm's micro physics and dynamic conditions is given, according to the data of radar, lightning detection and air sounding for 23 thunderstorms in Beijing and Shanghai area. Based on this and combined with previous studies, a warning method of the end of lightning activity is also gained. The main conclusions are as follows:1. The lightning activity has a strong correlation with the micro-physics and dynamic conditions of thunderstorm in both areas. In Beijing area, the echo volume above -15℃level with reflectivity exceed 30dBZ (V30t-15) has the highest correlation coefficients with total lightning frequency in all temperature levels with reflectivity exceed 30dBZ, which is better than that with 40dBZ and 50dBZ. The feature between echo volume and CG lightning frequency in the two sites is similar to the relationship of echo volume and CG lightning frequency in Beijing site.The result of power fit of the echo volume as a function of total lightning frequency and CG lightning frequency is better than linear fit. Compared the results of data fitting , it shows that the thunderstorm's Radar Echo Characteristics are similar in both sites.The statistic on 4 cases in Shanghai shows that the CG lightning activity has a good correlation with dynamic condition, in which the volume of updraft in strong echo area is the strongest. The correlation coefficients between V30t-15 and updraft volume, which include updraft volume in 30dBZ area above 0℃layer and above 0℃layer with speed exceed 5m/s and 10m/s updraft volume, are 0.93, 0.90 and 0.86. The result proves that the dynamic condition could be characterized by echo volume.2. Analyzing the case of Shanghai, it is found the following results. The CG lightning activity is divided into three periods, including initial period (P1), active period (P2) and decline period (P3). The CG lightning locates in the strongest echo area in P1 and P2, while in stronger echo place in P3. In three periods, the position of CG lightning locates in wind convergence region, in where the wind has lower speed. The CG lightning position does not locate in strongest updraft area but in stronger area.There is strong relationship between CG lightning activity and the features of echo and dynamic structure. There is no exceeding 50dBZ echo volume and faster than 10m/s updraft volume and no volume of lower than -10-2s-1 divergence in P1. In P2, the CG lightning frequency has a good consistency with all kinds of the volumes. In P3, there is no exceeding 50dBZ echo volume and no volume of more than 10-2s-1 vorticity existing, and the volume of updraft above 0℃layer has a dramatic decline.3. Through analyzing thunderstorms in Beijing site, two warning methods of the end of lightning activity are obtained. There are several parameters could be used as warning factor, which include 40dBZ echo top and V30t-15 with its percent of total thunderstorm volume and echo volume per flash.