Light reflected by an atmosphere containing irregular mineral dust aerosol

We simulate polarimetric satellite observations of sunlight reflected by a turbid atmosphere over the ocean. We determine the sensitivity of these observations with respect to the optical thickness and the single-scattering albedo of irregular mineral aerosol. Simulated results indicate that both quantities can be retrieved from simultaneous polarization and intensity measurements. Aerosol scattering is modelled using a true measured scattering matrix of irregularly-shaped mineral dust aerosol. We study the suitability of various approximations of the particle shape used for the numerical calculation of scattering matrices. Approximations with spheres or spheroids with a distribution of moderate axis ratios can lead to large errors of the simulated light intensities. A spheroidal approximation including extreme axis ratios is found to be the most appropriate one for simulations of light scattering by irregular mineral aerosol particles, if measured scattering matrices are not available.