Preliminary Observation Of The Process Of Negative Ground Lightning In Guangzhou Area Using Lightning Slow Electric Field Array

The process of lightning initiation and leading has always been the frontier hot spot of lightning physics research.Based on the thunderstorm data obtained by the Guangzhou Slow Electric Field Continuous Observation Array System,combined with the Guangdong-Hong Kong-Macao Lightning Location System location data and meteorological radar data of Guangdong,this paper analyzes the process of the cloud-to-ground flash.At the same time,the Guangdong-Hong Kong-Macao Lightning Location System's return stroke positioning efficiency is evaluated.This article draws the following interesting conclusions:1)Analyzing the first return strike at different locations of the thunderstorm core,it is found that the initial breakdown pulse clusters and the first return strike current in different precipitation areas are significantly different.53 cases of CG lightning process in the area of strong radar echo,The average values of its IBP duration(TD),IBP pulse interval time(Ti),ratio of peak field of biggest PB pulse to the first return stroke(IBP/RS),time from IBP to the first return stroke(TIBP-RS),return stroke interval(TRSi and first return stroke current(1)are 4.3 ms,117.5 ?s,0.24,77.2 ms,100.7 ms,and 22.67 kA respectively;98 cases of CG flash processes in the area of weak radar echo have characteristic parameters of 3.9 ms,71.3 ?s,0.21,61.7 ms,98.4 ms and 37.3 kA respectively.There are significant characteristic differences between the two in terms of time from IBP to the first return stroke,the interval of IBP pulses,and the current of the first return stroke.2)The characteristics of IBP in the process of ground-to-ground lightning in Guangzhou area are analyzed.The TD of IBP in Guangzhou area is concentrated in 1-5 ms,with an average of 3.96 ms;most Ti is in 30-150?s,accounting for 79%of the total;the average of TIBP-RS is 53.1 ms,most of which is between 15 ms and 75 ms,the proportion was 71.2%;the average value of IBP/RS is 0.24,and the proportion of IBP with an IBP/RS value less than 0.4 is 87.1%;the median of TRSi is 80.8 ms,and the average is 113.1 ms.The average number of strokes per flash is 4.96,the median is 4,and the proportion of single-returns is 6.75%.3)The characteristics of the IBP of the cloud flash process in Guangzhou area are analyzed.The TD arithmetic average of IBP in Guangzhou area is 9.75 ms and the median is 8.23 ms.The proportion of TD cloud flash cases in the range of 5 ms-15 ms accounted for 45.2%of the total.The arithmetic mean and median of Ti are 265.92 ?s and 228.20 ?s,respectively.4)Using the advantage of the observation array system that it can continuously collect lightning waveforms in a large range,the efficiency of the return strike positioning of the Guangdong-Hong Kong-Macao Lightning Location System is verified,and the reasons for the unsuccessful positioning of the return strike combined with the waveform are analyzed.It is found that the Guangdong-Hong Kong-Macao Lightning Location System has an efficiency of 93.5%in detecting ground-to-ground lightning strokes in the Guangzhou area.When there is a compact pulse cluster before the local flash,the positioning success rate is not high.The average interval time between the pulse cluster and the return stroke is 0.74 ms,and the pulse interval time of the pulse cluster is 13.2 ?s.