Observed summer variation and absorption characteristics of black carbon at Xi'an suburban

The data of black carbon, particle size concentration, visibility, and various meteorological variables observed during summer of 2011 at Xi'an Jinghe were used to calculate planetary boundary layer top height, aerosol absorption coefficient, and atmospheric extinction coefficient, and then derived single scattered albedo. Variation and absorption characteristics of black carbon were analyzed in this study. Results showed that the mean value of black carbon concentration was 6.07 μg/m3 with a range of 2.0~13.4 μg/m3 which are very different from Xi'an downtown. The ratio of black carbon concentration in PM1.0 was 21.9%, and the correlation coefficients between black carbon and particles mass concentration PM1.0, PM2.5, and PM10 were 0.69, 0.85, and 0.91, respectively. Black carbon concentration was affected by planetary boundary layer top, and the accumulation and transportation were affected by wind direction and speed. The ratio of aerosol absorption coefficient in atmospheric extinction coefficient was 21.9% with a range of 12% ~ 30%. Both coefficients show distinct diurnal cycle. The mean summer single scattering albedo was 0.76 ranging from 0.70 to 0.84.