Lightning activity and aerosols in the Mediterranean region

• We investigate the effect of aerosols on lightning activity over the Mediterranean Sea.
• The mean aerosol optical depth is lower than the mean aerosol optical depth of the days with lightning activity in 90% of the under study area.
• Increase in atmospheric optical depth will increase lightning activity and the percentage of days with lightning activity.
• The percentage of lightning activity days over a season changes according to seasonal atmospheric optical depth fluctuations.
• The positive correlation of both lightning activity and of days with lightning activity with atmospheric optical depth is consistent for all seasons.

In the framework of this study, the effect of aerosols on lightning activity has been investigated for the first time over the broader Mediterranean Sea. Atmospheric optical depth data retrieved by MODIS on board Aqua satellite and cloud to ground lightning activity data provided by ZEUS network operated by the National Observatory of Athens were analyzed for a time period spanning from 01/01/2005 up to 31/12/2013. The results indicate the importance of aerosols in lightning modulation. The mean aerosol optical depth (AOD) values of the days with lightning activity were found to be higher than the mean seasonal AOD in 90% of the under study domain. Furthermore, the increasing rate of lightning activity with increasing aerosol loading was found to be more pronounced during summertime and for AOD values up to 0.4. Additionally, the spatial analysis showed that the percentage of days with lightning activity during summertime is increasing with increasing AOD. Finally, time series showed similar temporal behavior between AOD seasonal anomalies and days with lightning activity differences. Both the spatial and temporal analysis showed that lightning activity is correlated to AOD, a characteristic consistent for all seasons.