Acta Optica Sinica, Vol. 40, Issue 24, 2429001 (2020)

Scattering Hygroscopic Growth Characteristics of Typical Haze Particles and Clusters

Abstract

In order to explore the scattering hygroscopic growth characteristics of haze particles caused by hygroscopicity, based on the humidity growth model of haze particles, we used the Mie scattering theory and multi-sphere T-matrix calculation method to study the scattering hygroscopic growth characteristics of five typical kinds of haze particles and their clusters when the incident wavelength was 532 nm and the relative humidity range was 60%-95%. The results demonstrate that for a single kind of haze particle, secondary water-soluble inorganic particles and clusters, such as sulfuric acid, ammonium sulfate, and ammonium nitrate, show prominent scattering hygroscopic growth. In comparison, the scattering hygroscopic growth is gentle for dust and inhibitory for carbonaceous aerosols. Meanwhile, the scattering hygroscopic growth of small particles is exponential, while that of large particles fluctuates with a negative growth trend. For the clusters of haze particles, the curve of scattering hygroscopic growth factor exhibits a declined overall increment. The volume fraction of the particle clusters has an obvious effect on the scattering hygroscopicity. Moreover, with an increase of the volume fraction, the curve of scattering hygroscopic growth factor has a higher fluctuation frequency and a smaller amplitude. However, the overall hygroscopic growth is determined by the size range and composition of cluster particles, and the size range of clusters has a greater impact. In conclusion, this study provides theoretical support for the research on the scattering hygroscopic growth characteristics and air pollution of haze particles.

keywords

• haze particles
• Mie scattering
• multi-sphere T-matrix
• scattering
• scattering hygroscopic growth factor