Aircraft Measurements of the Scattering Properties of Aerosols in Shanxi Province in Summer

The aerosol total scattering coefficient and its relation to the aerosol number concentration and meteorological conditions on cloudy, sunny, and cloudless days were analyzed using the integrating nephelometer and PCASP(Passive Cavity Aerosol Spectrometer Probe)-100X of three aerosol detection flights over Shanxi Province in the summer of 2013. The movement tracks and possible sources of aerosol pollution were discussed using the HYSPLIT(Hybrid of Single Particle Lagrangian Integrated Trajectory) model. The results showed that the range of aerosol total scattering coefficient varied from 0 Mm^-1 to 499 Mm^-1. The aerosol total scattering coefficient and aerosol number concentration on sunny days were significantly higher than those on cloudy and cloudless days. The aerosol total scattering coefficient decreased with altitude. Given the multiple pollution sources in the underlying surface, low wind speed, high relative humidity, and existence of a temperature inversion layer, the aerosol total scattering coefficient and aerosol number concentration increased. The ratio of the backscattering coefficient of the 550 nm wavelength was larger than 0.1. The aerosol total scattering coefficient was mainly influenced by the particle size of 0.1-0.5 µm, indicating that a significant fraction of particulate matter in Shanxi Province was attributed to fine-grained particles. Furthermore, the air pathways, which caused the high aerosol total scattering coefficient and aerosol number concentration, are mainly from the southwest. The contribution of local near-surface sources to aerosol total scattering coefficient is greater than that of long-distance transmission.