Comparison between two methods of pseudo 3D location and traditional waveform characteristics in lightning classification

Abstract:

This study compares two methods in the lightning classification, mainly positive and negative cloud-to-ground (CG) lightning and intra-cloud (IC) lightning, based on broadband observations of VLF emissions obtained by Beijing Lightning Network (BLnet). For the first method, the pseudo 3D location technique that is analogous to Betz et al. (2004) is utilized to separate CG and IC lightning on the basis of emission heights of the discharge processes. According to the polarity of the relative pulses, CG are further divided into +CG and –CG. Similar to the technique adopted in the U.S. National Lightning Detection Network (NLDN), the other traditional method takes advantage of the analyses of characteristics of the fast electric field or magnetic field waveforms in the time domain, including rising time, falling time, pulse width, peak ratios, etc. Through the comparison, it is achieved that the critical height of roughly 1 km is appropriate to be used to classify CG and IC lightning in the 3D lightning location system. In addition, for the distant lightning, the lightning types are tended to be classified as CG by these two methods.