The relation between aerosol optical depth and lightning from the tropics to the mid-latitudes

Recent studies indicate that for a certain range in aerosol loading values there is a positive correlation between aerosol amount and lightning activity. In the present study, the relationship between daily data of aerosol optical depth (AOD), derived from the Moderate Resolution Imaging Spectroradiometer (MODIS), and lightning density, recorded by the World Wide Lightning Location Network (WWLLN) are examined. The influence of aerosol particles on lightning density is found to depend on the range of AOD. The strongest lightning activity occurs on days with medium values of AOD. The days with low values of AOD (less than 0.15) are generally characterized by less lightning activity. Large aerosol concentrations, which correspond to AOD higher than 0.4, may be associated with a decrease in lightning activity and even inhibition of it. The results may indicate that the trends in lightning and AOD are not likely to be driven by the meteorological conditions, as it appears for a range of conditions, and the relations of proportionality between these two variables change in different ranges of AOD values. These results rather point toward possible aerosol effect on thunderstorms electrical activity.