Characteristics of hygroscopicity of atmospheric aerosols based on chemical component parameterization

In order to discuss the hygroscopic characteristics of atmospheric aerosols, the hygroscopic parameters κ were calculated based on the chemical composition of aerosols. The hygroscopic parameters were calculated firstly through PCA analysis, the main influencing chemical factors of hygroscopicity parameters κ were obtained; Secondly, based on the Köhler formula and the ZSR mixing theory, the hygroscopic parameters of each chemical component were weighted to get the corresponding hygroscopic parameters κchemical at each time. Finally, based on the κ-Köhler theory, differences between calculated value of hygroscopic characteristics and the theoretical values were discussed by inverting the characteristic parameters of hygroscopicity (optical and particle size hygroscopicity growth factor f(RH), gf). The iterative algorithm and the empirical formula obtained from previous studies were used to calculate the hygroscopic parameters, which was set to verify the accuracy of the chemical method. In addition, the relation between κchemical and visibility was also discussed. The results showed that the correlation coefficient between κchemical and κköhler was 0.78 and the root mean square error of the two was 0.031, which was at a low level. The ratio of the two was basically distributed in the range of 10% of the linear fitting error from the center. The correlation coefficient between the inversion of f(RH) and the instrument measurement f(RH)measured was as high as 0.99, which further proved a strong linear relationship between them. The gf had a high coincidence degree and correlation with the theoretical value gfNEP. When the visibility was less than 5km, the κNH4NO3 contribution to κchemical was 74.63%. © 2022, Editorial Board of China Environmental Science. All right reserved.