A look at the Relationship Between Tropospheric Nitrogen Dioxide and Aerosol Optical Thickness Over Lebanon using Spaceborne data of the Copernicus Programme

Over the decades, anthropogenic air emissions have resulted in the degradation of ambient air quality and posed major health risks. In this context, efforts have increased to understand the dispersion of pollutants in the earth's atmosphere, their spatiotemporal patterns, and long-term effect on climate. Of interest in this domain is the relationship between atmospheric aerosols and trace gases, and their influence on pollutant dispersion. As such, this paper addressed the relationship between tropospheric Nitrogen Dioxide (NO₂) and atmospheric aerosols; reflected by the Aerosol Optical Thickness (AOT) parameter over Lebanon. NO₂ column densities at low spatial resolution of about 7km were obtained from the Copernicus Sentinel 5p recently launched satellite, while AOT was retrieved at 10m resolution from the twin Sentinel-2 satellites. Results reveal a significant correlation between ln(NO₂) and AOT on several days in different seasons, with correlation coefficient r² up to 0.775. This allows the determination of hotspots at 10m resolution. These hotspots were mainly on the Lebanese coastline, the most urbanized area in the country.