Significant decrease of lightning activities during COVID-19 lockdown period over Kolkata megacity in India

https://doi.org/10.1016/j.scitotenv.2020.141321Get rights and content

Highlights

  • Average of PM10, NO2, SO2, O3, Aerosol reduced by −40 to −68% during the lockdown.

  • Daily reduction of PM10, NO2, SO2, O3, and Aerosol is about −0.153 to −1.099 μg/m3.

  • Air pollutants have significant impact on the climate phenomenon in Kolkata.

  • PM10, NO2, SO2, O3 and aerosol are positively linked with pre-monsoon lightning.

  • Average lightning flash decreases by −49.16% in Pre-monsoon, 2020 due to lockdown.

Abstract

The outbreak of COVID-19 has now created the largest pandemic and the World health organization (WHO) has declared social distancing as the key precaution to confront such type of infections. Most of the countries have taken protective measures by the nationwide lockdown. The purpose of this study is to understand the effect of lockdown on air pollutants and to analyze pre-monsoon (April and May) cloud-to-ground and inter-cloud lightning activity in relation to air pollutants i.e. suspended Particulate matter (PM10), Nitrogen dioxides (NO2) Sulfur dioxide (SO2), Ozone (O3) and Aerosol concentration (AC) in a polluted tropical urban megacities like Kolkata. After the strict lockdown the pollutants rate has reduced by more than 40% from the pre-lockdown period in the Kolkata megacity. So, decreases of PM10, NO2, SO2, O3 and AC have a greater effect on cloud lightning flashes in the pre-monsoon period. In the previous year (2019), the pre-monsoon average result shows a strong positive relation between the lightning and air pollutants; PM10 (R2 = 0.63), NO2 (R2 = 0.63), SO2 (R2 = 0.76), O3 (R2 = 0.68) and AC (R2 = 0.83). The association was relatively low during the lock-down period (pre-monsoon 2020) and the R2 values were 0.62, 0.60, 0.71, 0.64 and 0.80 respectively. Another thing is that the pre-monsoon (2020) lightning strikes decreased by 49.16% compared to the average of previous years (2010 to 2019). The overall study shows that the reduction of surface pollution in the thunderstorm environment is strongly related to the reduction of lightning activity where PM10 and AC are the key pollutants in the Kolkata megacity.

Keywords

COVID-19
Lockdown
Thunderstorm
Lightning
Air pollutant

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