Measurement of aerosol optical properties and their potential source origin in urban Beijing from 2013-2017

To investigate aerosol optical properties relevant to pollutant level controls in place in Beijing, particulate matters with diameter < 2.5 mu m (PM2.5) mass concentration, aerosol absorption (sigma(ap)) and scattering (sigma(sp)) 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, sigma(ap), and sigma(sp) all decreased, especially from 2014 to 2015. Note that, a significant decrease of d ap in autumn and a y in winter was responsible for the decrease of the year by year average. PM2.5, sigma(ap) and sigma(sp) exhibited a pronounced bi-peak diurnal variation, which was attributed to the traffic emissions. The wind dependence analysis revealed that sigma(ap) was mainly influenced by local emissions but sigma(sp) was influenced by both local emissions and regional transport. The potential spatial source origins of asp in Beijing were investigated using the potential source contribution function (PSCF). The results indicated that the potential source regions that influence sigma(sp) of Beijing were mainly from south and west of Beijing but slightly varied with different years and seasons.