Multitechnique Observations on the Impacts of Declining Air Pollution on the Atmospheric Convective Processes During COVID-19 Pandemic at a Tropical Metropolis

Gargi Rakshit; Soumyajyoti Jana; Animesh Maitra

doi:10.1109/LGRS.2021.3049887

Multitechnique Observations on the Impacts of Declining Air Pollution on the Atmospheric Convective Processes During COVID-19 Pandemic at a Tropical Metropolis

IEEE Geosci Remote Sens Lett. 2021 Jan 20:19:1001605. doi: 10.1109/LGRS.2021.3049887. eCollection 2022.

Authors

Gargi Rakshit¹, Soumyajyoti Jana¹, Animesh Maitra¹

Affiliation

¹ Institute of Radio Physics and Electronics, University of Calcutta Kolkata 700009 India.

Abstract

The present study addresses the impacts of reduced anthropogenic activities during the lockdown period of COVID-19 pandemic on the aerosol concentration, treated as heat absorbing agent, and on the related atmospheric processes, using ground-based and spaceborne measurements over a highly polluted Indian metropolis, Kolkata. The investigation reveals that reduced aerosol concentrations during the pre-monsoon of 2020, when the lockdown was implemented, decreased atmospheric instability as indicated by low values of the convective available potential energy (CAPE). This hindered the abundance of aerosols above the atmospheric boundary layer. Also, micro rain radar (MRR) observations showed a significant reduction of convective precipitation occurrences over Kolkata during this period. The back trajectory analysis has revealed the absence of continental component toward the wind clusters associated with rain occurrences during pre-monsoon 2020. This resulted in increased occurrences of stratiform rain events during the pre-monsoon of 2020 compared to the same period of previous years.

Keywords: Aerosols; COVID-19 pandemic; anthropogenic activities; atmospheric instability; back trajectory; black carbon (BC); convective processes; precipitation.

Grants and funding

This work was supported in part by the UGC Basic Science Research Faculty Fellowship through the University Grants Commission, New Delhi, India, under Grant F.18-1/2011(BSR), in part by the Council of Scientific and Industrial Research, HRDG under Grant 09/028(1040)/2018-EMR-I, and in part by Studies on Aerosol Environment at Kolkata located near the land-ocean boundary as a part of ARFI network under ISRO-GBP through ISRO under Grant SPL:GBP:ARFI:37.