Optical properties of chain-like soot with water coatings

Publication date: Available online 18 July 2019Source: ParticuologyAuthor(s): Meng Fan, Liangfu Chen, Liangxiao Cheng, Benben Xu, Jinhua Tao, Shenshen LiAbstractIn a moist atmosphere, the ageing process of aerosol can make the agglomerated soot particles compact, and cause them to be covered by a water coating. Based on the cluster‒cluster aggregation (CCA) algorithm, the models of chain-like soot with water coatings (Models A to E) were generated in this study. The superposition T-matrix method was employed to calculate their optical properties at 337, 550, 860, and 1060 nm wavelengths, with a focus on the impact of the soot inclusion morphology and water coating. Our results indicate that for particles with a looser soot-inclusion structure, there is a larger difference in the scattering phase function between them and the corresponding particles with a spherical soot core. The largest relative difference reached 51.8% at 337 nm. Impacted by the size parameter, the extinction cross section (Cext), absorption cross section (Cabs), scattering cross section (Csca), and single scattering albedo (SSA) increased as the water coating radius (Rwater) increased and incidence wavelength decreased. The traditional assumption of a spherical soot core can cause the Cext, Cabs, and Csca to be overestimated, and cause the SSA to be underestimated when the incident wavelength is 337 nm. At 1060 nm, the assumption can cause the Cext, Cabs, and Csca to be underestimated, and lead the...

Source: Particuology - July 18, 2019 Category: Science Source Type: research