Importance of shapes and compositions of wind-blown dust particles for remote sensing at solar wavelengths

[1] The quality of satellite aerosol retrievals depends critically upon the modeling accuracy of the aerosol optical properties. The optical properties of mineral aerosols depend on particle morphology, mineralogy, and state of mixing. Here we investigate how the realistic morphology and composition of dust particles affect the optical properties of dust mixtures by utilizing microscopy data that recently become available of dust samples collected in the atmosphere. The data were used to reconstruct the representative composition-shape-size (CSS) distributions and then the discrete dipole approximation technique was applied to calculate the optical properties. We demonstrate that the presence of sharp-edge, angular-type particles results in various differences in the scattering phase function, asymmetry parameter, optical depth and single scattering albedo compared to those of the volume-equivalent spheres or ellipses. These differences are sufficiently large as to affect the retrievals of aerosol optical properties from satellite and ground-based remote sensing observations at the solar wavelengths.