Optical and microphysical characteristics of aerosol in non-photochemical smog on the North China Plain

In January 2013, dense smogs with mass concentrations of fine aerosol of the order of hundreds of μg/m3 formed on the North China Plain, which attracted the attention of a wide range of specialists. A new non-photochemical mechanism of smog formation was discovered, in which rapid accumulation of sulfates occurs, caused by the catalytic oxidation of sulfur dioxide by molecular oxygen [1]. Of great interest is the microstructure of these smogs and the absorption capacity of the aerosol formed in non-photochemical smogs.
The analysis showed that the fine aerosol fraction dominates in non-photochemical smogs. Due to the rapid accumulation of sulfates, in some cases optically dense smogs are weakly absorbing (single scattering albedo of 0.99). In a significant number of cases, smog particles contain brown carbon in addition to black carbon.
Anomalous selective absorption of aerosol was detected in smog on the North China Plain (AERONET Taihu station). In this case, the imaginary part of the refractive index at a wavelength of 1020 nm reached approximately 0.11. Variations in the optical and microphysical characteristics of aerosols were analyzed when anomalous selective absorption occurred in smog. In particular, deviations from the bimodality of particle size distribution typical of winter smog in Beijing were detected.

1. Ermakov A.N. On a new mode of catalytic oxidation of sulfite in the presence of Mn(II) in excess metal ions // Kinetics and Catalysis. 2023. Vol. 64, No. 1. P. 86-96. [In Russian]