Positive Cloud-to-Ground Lightning Observed in Shah Alam, Malaysia based on SAFIR 3000 Lightning Location System

Abstract

Compared to negative cloud-to-ground (CG) lightning, positive CG are less frequent but can produce strokes with higher peak currents making them to be potentially more dangerous. This paper presents an investigation on positive cloud-to-ground (CG) lightning activity in Shah Alam, Malaysia recorded by SAFIR 3000 lightning location system (LLS). For this study, a total of 572,282 LLS data from 2013 to 2015 were analyzed. We found that only 1.6% of the total CG flashes were contributed by positive CG while the remaining 98.4% were dominated by negative CG. We also observed that the occurrence of positive CG follows the weather pattern of Malaysia, with a strong connection between positive CG and rain events. Most positive CG occurred in November, while the least occurred in February. Our results showed that the highest peak current for positive CG was 86.7 kA with average geometric mean and median values of 14.2 kA and 12.8 kA, respectively. The negative CG recorded a higher peak current of 139.6 kA with average geometric mean and median values of 13.6 kA. Previous studies conducted on positive CG in Malaysia may be an overestimate if weak positive flashes were included in the analyses. Due to a limited number of existing studies on positive CG conducted in Malaysia, more researches should be conducted.