Aerosol mixing state implications for remote sensing

This work explores directional and polarimetric characteristics of light scattered by inhomogeneous particles using the core-shell model. In a series of numerical simulations, constrained by microscopic observations of coated particles (Unga et al., 2018), we analyze manifestation of core-shell particle structure in retrievals of aerosol optical and microphysical properties. The observational configurations that involve polarization and directional scattering information are found to be sensitive to the particle inhomogeneity. The side and backward scattering appears as particularly influenced by the core-shell particle structure. We thus suggest that the advanced remote sensing measurements can detect aerosol coating. Given that the contrast in the refractive indices is strongest in case of solid core and liquid shell, the approach can provide the valuable information on aerosol water fraction. Parameterization of core-shell aerosol model in the retrieval algorithms is also proposed. Measurements by POLDER-type satellite sensors and ground-based photometers (AERONET) are in the scope. Acknowledgements This work is supported by the Labex CaPPA (Laboratory of Excellence Chemical and Physical Properties of the Atmosphere) project, which is funded by the French National Research Agency through the PIA (Programme dInvestissement dAvenir) under contract ANR-11-LABX-0005-01. References Unga, F., Choel, M., Derimian, Y., Deboudt, K., Dubovik, O., Goloub, P. (2018), Microscopic observations of coreshell particle structure and implications for atmospheric aerosol remote sensing, J. Geophys. Res., 123, 13944-13962, 10.1029/2018jd028602.