Influence of the COVID-19 lockdown on lightning activity in the Po Valley

The relationship between aerosol concentration and lightning is complex. Aerosols can act as cloud condensation nuclei, contributing to the formation of cloud droplets, cloud electrification and lightning, while high concentrations of aerosols can contribute to a decrease in lightning due to radiative effects. Meteorology plays a dominant role in lightning activity, distorting the effect of aerosols. More measurements, as presented here, are needed to establish the complex relationship between aerosols and lightning. The Po Valley, a heavily industrialized region, was highly affected by the COVID-19 lockdown. The reduction of non-essential activities and mobility coincided with a significant drop in pollutant concentrations and lightning. We investigate the relationship between lightning, meteorology and aerosols. We find that the variation in lightning during the lockdown as compared to recent years cannot be fully attributed to meteorology. ~60 ± 10% of the observed decrease is attributed to meteorology, and ~40 ± 10% to the reduction in aerosol emissions. © 2021FJPI acknowledges the sponsorship provided by the Federal Ministry for Education and Research of Germany through the Alexander von Humboldt Foundation. Additionally, this work was supported by the Spanish Ministry of Science and Innovation, under projects PID2019-109269RB-C43 and FEDER program. SS acknowledges a PhD research contract through the project PID2019-109269RB-C43. FJGV and SS acknowledge financial support from the State Agency for Research of the Spanish MCIU through the ‘Center of Excellence Severo Ochoa’ award for the Instituto de Astrofísica de Andaluca (SEV-2017-0709).Peer reviewe