Mutual relationship between surface atmospheric pollutants and CG lightning in Tehran area.

The mutual relationship between surface atmospheric pollutants and Cloud-to-Ground (CG) lightning is studied in the Tehran area for the first time. The impact of surface pollutant concentration of PM on CG lightning initiation, as well as the production of NO and surface ozone derived by lightning occurrence is investigated. To proceed, the reports of thunderstorm occurrence, including CG lightning in the Tehran area have been collected for years of study from the Iran meteorological organization (IRIMO). The surface pollution data are obtained from the Air Quality Control Center (AQCC) for several stations in the area of interest. The number of lightning (NoL) associated with the selected dates is obtained using the World Wide Lightning Location Network (WWLLN). The correlation coefficients associated with the CG lightning and the concentrations of PM, NO, and surface ozone are calculated. The hourly variations of accumulated NoL and NO and surface ozone are also compared for 24 hours before and after the lightning activity for four days of study during the years of 2009-2013. The results show that there is a positive correlation between PM10 concentration and lightning flash number, obtained from observational data of WWLLN. Moreover, the comparison of NoL and surface pollutant concentration indicates a clear positive contribution from CG lightning in NO and ozone production. In days with a considerable number of lightning occurrences, the comparison of the hourly average of NO and O concentrations with the lightning flash number reveals that NO decreases, and O increases due to the significant increases of lightning strikes.