Spatial Variation of Tropospheric NO2 Concentration During First Wave CoVID-19 Induced Lockdown Estimated From Sentinel-5 Precursor

CoVID-19 pandemic has forced many countries to shut down their industries as most of these countries observed complete state-wide lockdown during the first wave of this contagious virus. Factories and vehicles on the road are a major source of nitrogen dioxide (NO2), which is also one of the major air pollutants. The emission of NO₂ is considered as a good indicator of prevalant global economic activities as its predominant corollary affairs typically involve industrial oprtaions and these emissions are evidently visible from space. Sentinel-5 Precursor (launched in July 2018), equipped with spectrometer Tropomoi (Tropospheric Monitoring Instrument), is a low-earth-orbit atmosphere mission satellite dedicated towards monitoring air pollution sensing remotely. This study is focused primarily on, estimation and variation of NO2 emission over different parts of the world, before and during the first wave of CoVID-19 epidemic (07 weeks duration). It is found that in most of the countries during the lockdown period (7 weeks), air quality was cleaner by about 40 to 50 % over the last year, mainly due to the shutdown of industry and traffic activities. The technology is quite promising and provides a tool to access if a country or place followed complete lockdown.