Change Detection of Incident Light Over Indian Sub-Continent During Covid-19 Lockdown Using Satellite Imaging Data

The World Health Organization (WHO) declared the outbreak of the COVID-19 virus as a pandemic on 11 March 2020. As a preventive measure to arrest its spread, the Government of India implemented one of the largest lockdowns in human history on 25 March 2020. This led to closure of a large number of industries and restriction on people movement. Such a measure reduced the concentration of major pollutants in the atmosphere. Present study quantified the impact of change in particulate air pollutants in terms of aerosol optical depth (AOD) on incident light energy over the Indian Sub-continent using satellite imaging observations at 10:30 AM and a radiation transfer algorithm. Change in incident photosynthetically active radiation (IPAR) was used to denote change in level of light energy before and after the commencement of the lockdown. A net increase in IPAR up to 25% was estimated due to lockdown.