Characterization of the major aerosol species over Egypt based on 10 years of CAMS reanalysis data

Abstract

This study investigates the spatiotemporal distribution of the major aerosol species (sulfate, organic matter, black carbon, dust, and sea salt) and their contributions to the total aerosol optical depth (AOD) over Egypt from 2010 to 2019 by using the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis data. Dust was the major aerosol species, with an average contribution of 48% to the total AOD. The highest concentrations of dust were found in spring because of the significant impact of the Khamsin wind in carrying sand aerosols from deserts. The dispersion of dust aerosols is greatly influenced by topography. While lowlands, such as the Qattara Depression, accumulate sand aerosols from the surroundings, the mountainous highlands disrupt horizontal diffusion. El-Farafra and Siwa Oasis, which are close to the Qattara depression, had significant dust contributions to the total AOD. Because the Nile Delta, Suez Canal, and Nile River regions are densely populated and industrialized, organic matter and sulfate showed considerable contributions of 24% and 23%, respectively, to the total AOD. The highest concentrations of organic matter and sulfate were found in summer because of the high temperatures that accelerate photochemical reactions. While fossil fuels and biomass burning increase carbon emissions in cities such as Cairo and Tanta, shipping in the Suez Canal and natural gas flares in the eastern Mediterranean increase sulfate aerosols in cities such as Port Said, Suez, and Arish. Black carbon and sea salt were the minor aerosol species, with average contributions of 3% and 2%, respectively, to the total AOD.