Comparison of equations used to estimate soot agglomerate absorption efficiency with the Rayleigh-Debye-Gans approximation

Abstract The contribution of soot aerosols to radiative forcing and climate change depends on their optical properties. Since these are agglomerates composed quasi-spherical primary particles (usually small with respect the radiation wavelength), properties can be calculated following Rayleigh-Debye-Gans approximation, which considers as independent absorbers scatterers, corrections made account for multiple scattering absorption within agglomerate. A variety equations used compared wavelength. In this study, results Rayleigh, Bohren Huffman, simplified Dobbins Megaridis have been from exact Mie efficiency. This comparison has individual different diameters an ensemble composing It shown that some largest a typical agglomerate may not behave Rayleigh at short wavelengths, contributing errors in estimation Both Huffman useful extend application range equation, thus reducing accumulated error analysis performed several complex refractive index spectra. To choose best equation particular application, wavelength spectrum particle sizes should considered, aiming compromise between simplicity accuracy.