A preliminary assessment of lightning activity around a South African mining town, eMalahleni

Abstract

This paper presents the results of a preliminary study of lightning activity around eMalahleni, a South African town which is surrounded by an estimated 160 mines and 13 coal power plants. This area also falls within one of most polluted regions of South Africa with recorded particulate matter (PMio) concentrations of about 80 μgm−3 between 2009 and 2012. Cloud to ground (CG) lightning flash data from the South African Lightning Detection Network (SALDN) for 2013 was used to calculate the spatial distribution of overall flash density, positive flash density and average multiplicity in the region within a 250 km radius of eMalahleni. A total of 1127186 CG flashes were recorded in the area in 2013. The highest average flash densities in excess of 12 flashes/km2/year were observed over the regions that are part of the Drakensberg escarpment. Flash densities ranging between 6 and 12 flashes/km2/ year were also observed near some of the mines that are not on the Drakensberg escarpment. Positive flash densities less than 1 flash/km2/year were observed near mines and power stations compared to flash densities greater than 1 flash/km2/year observed elsewhere. This might be an indicator that both elevation and mining activities are affecting CG lightning activity in this region. However, more data analysis needs to be conducted before conclusions can be drawn on the effects of mining and elevation on lightning activity in the region.