Statistical analysis of characteristic parameters for multi-return stroke of cloud-to-ground lightning in Fujian

Based on the ADTD lightning locating data in Fujian province from 2013 to 2015 and according to the characteristics of multi-return stroke of cloud-to-ground lightning (referred to as multiple strokes lightning), we have consulted a distinguishing index for multiple strokes lightning, and performed the analysis of the distribution pattern and characteristic parameters of multiple strokes lightning in Fujian. The results show that the frequency of multiple strokes lightning accounts for 30.58% of the total frequency in Fujian. Average stroke number is 1.49, in which the average positive and negative lightning stroke numbers are 1.02 and 1.52. Negative and positive lightning stroke numbers are 12 and 4, respectively. The average current intensity of the first and follow-up strokes for positive multiple strokes lightning are 45.03 kA and 26.81 kA, and their maximum values can reach 163.13 kA and 149.21 kA, respectively. Those for negative multiple strokes lightning are -11.52 kA and -9.23 kA, and their maximum values can reach -103.71 kA and -96.12 kA, respectively. It has been found that the first strokes mostly produce greater current intensity than follow-up strokes. The interval of strokes lightning is quasi normal distribution, in which strokes frequency is the most when time interval is from 60 ms to 90 ms, and its arithmetic mean is 135.36 ms. The daily peaks of positive and negative multiple strokes lightning frequency appear at 17 p.m. and 16 p.m., respectively. Multiple strokes lightning occur frequently between May and September in Fujian.