Evaluation of Aerosols Impact on global and direct irradiance attenuation under clear sky condition: A case study in Morocco

Solar energy is a promising alternative for reducing the consumption of fossil fuels. However, solar potential depends on several atmospheric parameters. When no clouds are present, aerosols are the primary source of solar radiation attenuation. This study examines the impact of aerosol optical depth on the attenuation of solar irradiance under clear sky conditions. For this purpose, aerosol data from satellite databases and irradiance data from high-performance meteorological stations installed in two sites in Morocco were exploited. Under clear sky conditions, the results showed a decrease in global horizontal irradiance relative to the global irradiance at the top of the atmosphere of 24% for aerosol optical depth values of 0.02 and exceeding 53% for 0.6. Aerosols have a more significant impact on the direct normal irradiance under clear sky conditions; over the test data, a decrease of 66% was observed for the direct normal irradiance according to the extraterrestrial irradiance for aerosol optical depth of 0.2 and reaching 92% for 0.6.