Application of the Rayleigh-Debye-Gans (RDG)theory for determining optical properties of biomass burning aerosols.

Biomass burning emissions are a major source of fractal aggregates which are clusters of spherules forming aerosols of non-spherical shape. Both the developed and developing world are subject to biomass burning events through agricultural burning, wildfires, and domestic burning applications. Accurate quantification of their optical properties is important both for their measurement and for predicting their radiative effect on climate. RDG assumes that each monomer in the aggregate interacts independently with radiation, by neglecting multiple scattering and shadowing. Absorption is an incoherent process and as a result the absorption of the aggregate is equal to the number of monomers, N, times the absorption of a single monomer. TEM images are used to determine the size parameters of the fractal aggregates. We report use of the RDG theory to fit experimentally measured optical properties to extract the refractive indices of biomass burning aerosols.