Numerical Analysis Of Soot Aggregates Morphology Influence The Light Scattering Properties In Atmospheric Aerosol

Soot aerosols can absorb solar radiation, atmospheric visibility, causing the greenhouse effect, its absorption and scattering effects on the solar radiation have become a very important factor on the environment and climate change. With further understanding of the environmental effects of soot aerosol, black carbon aerosols have been studied by many scholars as an important aspect of environmental problems. The study of soot aerosol light scattering properties can provide the key theoretical analysis basis for atmospheric environmental monitoring, weather forecasting and aerosol concentration detection.In this paper, the scattering properties of soot aggregates are studied based on cluster- cluster aggregation model and T matrix, and the changes of light absorption and scattering coefficient are also analyzed. For the homogeneous soot aggregates, soot aggregates with fractal dimension and the former to the morphological properties of the factors are studied by the CCA model, the soot aggregates scattering properties of different morphological parameters of multi group particle number are calculated by using the T matrix. For the soot aerosol which is in the environment of high relative humidity of atmosphere, the optical constants and the equivalent complex refractive indices of the soot aggregate coated with water are calculated by using the Maxwell-Garnett effective medium theory. For a single particle of soot, the extinction, absorption and scattering efficiency factor values of soot particle are calculated by Coat-Mie theory in different relative humidity. For particles of soot aggregates, the change situation of the soot aggregates optical properties in different relative humidity are calculated by using MG-T theory. For the heterogeneous soot aggregates, the equivalent optical constants of mixtures are calculated by using Maxwell-Garnett theory. The scattering properties of external mixing soot aggregates are studied by using T matrix. Based on Coat-Mie theory and MG-T theory, the scattering properties of internal mixing soot aggregates are calculated. At the same time, the variation of soot aggregates absorption and scattering coefficients of two kinds of mixture are also analyzed. The results show that the light scattering properties of soot aggregates are changing with the fractal structure, air relative humidity and mixed state changing. And the light scattering properties of aggregates increase with the size of the fractal parameters, air relative humidity, mix ingredients. The influence of aggregates light scattering properties which affected by the structure can not be ignored. The analysis of soot aggregates scattering properties can provide a theoretical basis for the soot aerosol concentration.