A Simple Current waveform model for Narrow Bipolar Pulses

A narrow bipolar pulse (NBP) refers to the distant electromagnetic signatures in very low frequency(VLF)/low frequency(LF) bands produced by a distinct class of impulsive and powerful intra-cloud discharge called Narrow Bipolar Events(NBE). In this presentation we propose a self-consistent model which includes three parameters to model narrow bipolar pulses. According to our model the producing current waveform of NBE was governed by two of them and can be directly derived from observed narrow bipolar pulse waveform. The model was applied to 144 negative NBEs and 1395 positive NBEs. Among 79 negative NBEs and 761 positive NBEs which gave the perfect fit between model and measured field waveforms, the results indicated that some of NBEs will be produced by the double-exponential decaying current while many other NBEs will produce the sinusoidal oscillation current in waveform.