Remote Measurement of the Lightning Impulse Charge Moment Change Using the Fast Electric Field Antenna

Wenhao Hou,Qilin Zhang,Jie Li,Xun Cui,Hongsheng Wang,Jiaying Gu,Xue Jiao,Yaojun Wang,Bingzhe Dai

doi:10.3390/rs14030724

Abstract

The impulse charge moment change (iCMC) is an important electrical property of cloud-to-ground (CG) lightning. In this paper, a new method of measuring the iCMC at distances of several hundred kilometers is proposed. The method is based on the vertical electric field below 1 kHz measured by the widely used fast electric field antenna with low frequency/very low frequency (LF/VLF) band. The impulse response of Earth-ionosphere waveguide (EIWG) is modeled using a finite difference time domain (FDTD) method considering an anisotropic ionosphere. By comparing the observed waveform with the simulated impulse response, the lightning discharge is classified into the impulsive discharge and the non-impulsive discharge. For the impulsive discharge, its iCMC is obtained directly by comparing the measured ELF waveform to the modeled impulse response at the same distance. For the non-impulsive discharge, its current moment waveform is assumed to be a sum of two Heidler’s functions, and the genetic algorithm is used to search the unknown parameters in the functions. The good agreement between the measured ELF waveform and the simulated waveform implies that the extracted current moments are reasonable. This method can be used to continuously monitor the lightning iCMC in a given time and space.

Highlights

The lightning charge moment change, which is defined as the product of charge transferred from cloud to ground by the discharge and the lightning channel height, is an important electrical property of the CG lightning [1,2]
The current moment waveform is assumed to be a sum of two Heidler’s functions, and the genetic algorithm is used to search the unknown parameters in the function
We developed a new method to measure the lightning impulse charge moment change (iCMC) within 2 ms at distances of several hundreds of kilometers

Summary

Introduction

The lightning charge moment change, which is defined as the product of charge transferred from cloud to ground by the discharge and the lightning channel height, is an important electrical property of the CG lightning [1,2]. Different from the peak current which is commonly provided by the widely used lightning locating systems, the iCMC is a parameter related to the charge. The charge moment change and peak current are not always well correlated [3,4]. The charge moment change is an important parameter to evaluate the characteristics of lightning discharges [4,5], the formation of transient luminous events (TLEs) [6,7,8,9,10,11] and terrestrial gamma-ray flashes (TGFs) [12,13]. Previous measurements on the lightning charge moment change were conducted using the recorded lightning electromagnetic (EM) waveforms in the extremely low frequency band

Methods

Results

Discussion

Conclusion