Abstract View
The Fractal Characteristics of Atmospheric Coated Soot: Implications for Morphological Analysis
Jie Luo, Qixing Zhang, CHENCHONG ZHANG, Yongming Zhang, Rajan K. Chakrabarty, University of Science and Technology of China
Abstract Number: 361
Working Group: Aerosol Physics
Abstract
Soot particles, as a major light absorber in the atmosphere, contribute great positive radiative effects to the climate. The radiative effects of soot have gained increasing interest in recent years, while there are still large uncertainties. Multiple modeling studies have shown that various soot morphologies can lead to large uncertainties in the estimations of radiative properties, while the morphological characteristics of soot, especially for coated soot, are still not fully understood. Here we numerically investigate the variation of fractal characteristics of soot particles as they are coated. We find the ideal fractal law can fit the morphologies of coated soot only when the radius of gyration of coated soot is identical to that of the soot core. In that case, the fractal dimension of coated soot is close to that of the soot core, which can explain the unchanged fractal dimension as soot is evenly coated. Our results also show that the fractal parameters of coated soot at different size scales can be varied, so the ideal fractal law does not fit the structures of unevenly coated soot. The results of the Q-space analysis indicate that if soot particles are unevenly coated, the power-law exponent of the structure factor versus the scattering wave vector tends to -4 for heavily coated soot. It implies that heavily, unevenly coated soot exhibits the characteristics of nearly spherical particles. We anticipate our research provides morphological constraints for coated soot particles in further modeling studies.
Citation: Luo et al. (2021): The fractal characteristics of atmospheric coated soot: Implication for morphological analysis. J. Aer. Sci., 157, 105804.