Detection of M-components and return strokes in upward and downward lightning flashes

Abstract

This work aimed to investigate which pulses (M-components and/or subsequent return stroke) of the upward lightning are detected by BrasilDAT lightning location network. It was found that, these pulses are similar to downward lightning pulses and therefore, they were well detected by the network. This report is based on a set of 29 upward lightning and 16 downward lightning whose strike points are known. All lightning used were recorded in the Jaraguá Peak region. High-speed cameras and electric field sensors were used in this analysis to find out the rise time of the waveform and the peak value of the electric field. The comparison with the pulses of the downward lightning recorded by cameras allowed us to validate the BrasilDAT network, determining the detection efficiency and location error. We found a detection efficiency of 37-56%, and a location error of approximately 600 meters. It was observed that the M components of the upward lightning resemble the subsequent return strokes of the downward lightning because the luminosity prior to the pulse is low and the rise time of the electric field waveform is short. The current peaks of the pulses of the upward and downward lightning were intense. These facts explain why BrasilDAT captured these pulses, since the networks tend to discard pulses with low intensity and long rise times.