Using Sentinel-5P time-series products for Nitrogen Dioxide (NO2) Spatio-Temporal Analysis over Europe During the Coronavirus Pandemic Lockdown

Nitrogen dioxide (NO²) is one of the main air quality pollutants of concern in many urban and industrial areas worldwide. Being emitted by fossil fuel burning activities including mainly road traffic, the NO² pollution is responsible for population health degradation and secondary pollutants formation as nitric acid and ozone. In the European region, almost 20 countries exceeded in 2017 the NO² annual limit values imposed by European Commission Directive 2008/50/EC (EEA, 2019). Therefore, NO² pollution monitoring and regulation is a necessary task to help decision makers to search for a sustainable solution for environmental quality and population health status improvement. In this study, we propose a comparative analysis of the tropospheric NO² column density spatial configuration over Europe between similar periods from 2019 and 2020, based on ESA Copernicus Sentinel-5P products. Our results highlight the NO² pollution dynamics over the abrupt transition from a normal condition situation to the COVID-19 outbreak context, characterized by short-time decrease of traffic intensities and industrial activities, this situation being also reflected by the national level statistics referring to COVID-19 cases and economic indicatiors. The validation approach provides high correlation between TROPOMI derived data and independent data from ground-based observations with encouraging values of the R² ranging between 0.5 and 0.75 in different locations.