Analysis of mixed aerosol environment and optical characteristics based on OPAC

Due to the complex sources of aerosols in coastal regions in China. The Optical Properties of Aerosols and Clouds(OPAC) isn’t been able to cover the microphysical and optical properties of coastal mixed aerosols. This research employs an external mixing method to mix the maritime clean aerosols with other aerosol types in different proportions by volume. Four mixed aerosol environments were defined, which are clean marine-average continent environment (SS-CV), clean marine-polluted continent environment (SS-CP), clean marine-urban environment (SS-UR), and clean marine-desert environment (SS-DESERT). Simulation experiments were conducted on the aerosol optical parameters(including extinction coefficient (EXT) and LiDAR ratio (SA)) of these four environments at 550 nm and 1000nmwavelengths, in order to analyze the variation of aerosol optical parameters with relative humidity (RH) and component number density in different mixed environments. The results indicate that EXT of aerosols in the four mixed environments increased with RH in both wavelengths, and EXT of aerosols increased linearly with the number density of components. The variation of SA is influenced by multiple factors such as wavelengths, relative humidity, and Multi factor effects of relative humidity and component number density. For the SS-CV, SS-CP, and SS-UR mixtures, water soluble and accumulation mode sea salts have a greater influence on SA and EXT, while for the SS-DESERT mixture, accumulation mode mineral and mode sea salts particles have a more substantial effect. This study enhances the understanding and prediction of optical property changes in complex aerosol environments near marine regions.