Surface Aerosol Optical Properties during High and Low Pollution Periods at an Urban Site in Central China

Boming Liu ； Wei Gong ； Yingying Ma ； Ming Zhang ； Jian Yang ； Miao Zhang

《Aerosol and Air Quality Research》 18卷12期 (2018/12) Pp. 3035-3046

https://doi.org/10.4209/aaqr.2017.12.0565

摘要

The aerosol scattering (σ_(sp)) and absorption (σ_(ap)) coefficients and single scattering albedo (SSA) were continuously measured and analyzed at an urban site in Wuhan of central China from November 2014 to July 2017. The average σ_(sp) (532 nm), σ_(ap) (532 nm), and SSA in Wuhan during the study period were 244 ± 212 Mm^(-1), 27 ± 17 Mm^(-1), and 0.86 ± 0.09, respectively. The aerosol optical properties had pronounced and distinctive diurnal cycles in the Wuhan area. The σ_(sp) and σ_(ap) exhibited the highest values between 06:00 and 08:00 local time (LT) and the lowest values between 14:00 and 16:00 LT, which was mainly due to being coupled with increasing traffic emissions. PM_(2.5) was a major contributor to the large optical parameters. During pollution periods, the mean σ_(sp) (624 Mm^(-1)) was roughly 3 times that during clean periods (214 Mm^(-1)), and the σ_(ap) (58 Mm^(-1)) was about 2.5 times that during clean periods (24 Mm^(-1)). The wind speed and direction also strongly affected the aerosol optical properties during the different periods. The high σ_(sp) and σ_(ap) values for the pollution periods were accompanied by calm winds (0-2 m s^(-1)), from 0° to 45°, whereas the low σ_(sp) and σ_(ap) values of the clean periods were observed with high wind speeds (above 4 m s^(-1)), from 0° to 90°. Moreover, the σ_(ap) showed a clear positive correlation (R^2 = 0.412) with the PM_(2.5) concentrations for the clean periods, whereas the σ_(sp) had a good positive correlation (R^2 = 0.406) with the PM_(2.5) concentrations during the pollution periods.

關鍵字

Aerosol scattering coefficients ； Aerosol absorption coefficients ； Single scattering albedo ； Haze pollution ； PM_(2.5)