Lightning during the COVID-19 pandemic in Brazil

Area of Science:

• Atmospheric Science
• Environmental Science
• Meteorology

Background:

• Air pollution is known to influence atmospheric phenomena, including lightning.
• The COVID-19 pandemic prompted unprecedented reductions in human activity and associated air pollution globally.
• Understanding these impacts is crucial for atmospheric modeling and safety.

Purpose of the Study:

• To investigate the effects of a significant decrease in air pollution on lightning characteristics.
• To compare lightning changes in two major Brazilian cities during a specific period of reduced pollution.
• To establish a correlation between pollution levels and lightning activity.

Main Methods:

• Analysis of lightning data from São Paulo and Belo Horizonte during a period of reduced air pollution (March 20 - April 02, 2020).
• Comparison of lightning flash ratios (cloud-to-ground vs. intracloud, positive vs. negative) and average peak currents.
• Statistical analysis to determine the significance of observed changes compared to previous years' data.

Main Results:

• In São Paulo, a significant decrease in the ratio of cloud-to-ground to intracloud flashes was observed.
• The average peak current of negative cloud-to-ground flashes also significantly decreased in São Paulo.
• In Belo Horizonte, a significant increase in the ratio of positive to negative cloud-to-ground flashes occurred.

Conclusions:

• The study demonstrates a direct link between reduced air pollution and altered lightning characteristics.
• Different cities exhibited distinct responses in lightning activity to decreased pollution levels.
• These findings highlight the complex relationship between anthropogenic aerosols and electrical phenomena in the atmosphere.