Occurrence of Positive Cloud-to-Ground Lightning During Flash Flood in Malacca

Abstract

In the tropics, the occurrence of positive Cloud-to-Ground (CG) flash is less frequent, but it can produce strokes with higher peak currents than negative CG. Thus, positive CG flashes are potentially more fatal and dangerous than negative CG flashes. Moreover, a recent study found that positive CG flashes are related to flash flood occurrence. In this paper, electromagnetic fields of 63 positive CG flashes detected from a storm when a flash flood event happened in Malacca on 20 October 2021 are analyzed. All positive CG flashes have been detected close to the lightning sensor located in Universiti Teknikal Malaysia Melaka where some of the flashes were detected within reversal distance. The characteristics of the slow electric field changes show that the cloud responsible for the flash flood event was having an ordinary tripolar charge structure.