LAUSR

Abstract To investigate aerosol optical properties relevant to pollutant level controls in place in Beijing, particulate matters with diameter σ a p ) and scattering ( σ s p ) coefficients were continuously measured from January 2014 to March 2017 at an urban site Peking University Atmosphere Environment MonitoRing Station (PKUERS). Our results showed that PM2.5, σ a p , and σ s p all decreased, especially from 2014 to 2015. Note that, a significant decrease of σ a p in autumn and σ s p in winter was responsible for the decrease of the year by year average. PM2.5, σ a p and σ s p exhibited a pronounced bi-peak diurnal variation, which was attributed to the traffic emissions. The wind dependence analysis revealed that σ a p was mainly influenced by local emissions but σ s p was influenced by both local emissions and regional transport. The potential spatial source origins of σ s p in Beijing were investigated using the potential source contribution function (PSCF). The results indicated that the potential source regions that influence σ s p of Beijing were mainly from south and west of Beijing but slightly varied with different years and seasons.