Study on the optical properties of sulfate coated dust aerosol particles during haze episodes

The complex mixing state of sulfate and mineral dust particles is formed through a series of chemical reactions, which bring great difficulties to understand the optical properties of atmosphere aerosols during haze episodes. Therefore, it is of great significance to clarify the influence mechanism of sulfate core on the optical properties of mineral dust particles. In this paper, a core-shell ellipsoidal structure model of dust and sulfate (D-S) aerosols was established based on the actual haze conditions according to mixing structure change in the action process between sulfate and mineral dust particles. The influence of mixing ratio on the optical properties of monodisperse dust-sulfate particles at four selected wavelength (0.44, 0.675, 0.87 and 1.02 μm) was studied by using the T-matrix method. The results show that the influence of mixing ratio on the optical properties of D-S particles is mainly in the Mie scattering region, while the effect of mixing ratio is not obvious in the Rayleigh scattering region. When the mixing ratio is less than 0.3, the sulfate shell plays a dominant role in the particle scattering characteristics, while the mixing ratio is greater than 0.7, the particle scattering characteristics are mainly affected by the dust core. In the range of 0.3-0.7, the scattering characteristics are influenced by D-S, and maybe stronger or weaker than any kind of pure particles. The research is of great significance to understand the mixing structure and optical properties of individual aerosol particles during haze aging process. © 2021, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved.