Decay form of the echo amplitude and echo phase of typical early/fast VLF event on 19.8 kHz signal

Abstract

In this paper, the echo amplitude (M) and echo phase (ø) of typical early/fast events on NWC (19.8 kHz) signal received at Suva, Fiji, are modelled to determine their form of recovery (decay). We applied logarithmic and exponential fitting formulas for M and ø obtained using a simple theoretical model of VLF wave scattering from lightning-induced electron density perturbations in the lower ionosphere and found that they are highly logarithmic.