Characteristics of Vertical E-field Waveforms Associated with Return-strokes on Southeastern Sea of Kyushu

Abstract

The lightning detection network has widely spread, and the research has actively been done by using the location of the lightning striking point and/or the peak current obtained by the network. Recently, Cummins et al. have clarified that the maritime return-stroke current on southern and eastern sea of the USA is higher than the inland return-stroke current by using the results obtained by NLDN. In this paper we compare the inland and the maritime return-stroke current in southeastern part of Kyushu by using the data obtained by JLDN. In case of negative first strokes, the maritime return-stroke current is higher than the inland stroke current in contrast to the cases of negative subsequent and positive first strokes. The authors investigate characteristics of the electric field waveforms associated with maritime negative and positive strokes in summer. As a result, it is pointed out that high frequency of occurrence of time-derivative of E-field waveforms having multiple pulses close to the dominant peak might be one of causes of the observed difference between the maritime and inland stroke currents in case of negative first strokes.