北京城区污染过程气溶胶光学特性观测分析

Based on the continuous observation data of lidar, the aerosol backscattering coefficient (355/532/1064 nm), extinction coefficient (532/607 nm), depolarization ratio (532p/532s), lidar ratio (532nm) and backscatter-related Ångström exponent (355/532nm and 532/1064nm) are retieved. Then, the aerosol optical properties of three different pollution episodes (air pollution/polluted dust/pure dust) in Beijing in October 2019 are analyzed. Results show that the air pollution aerosol depolarization ratio at 532nm (Ångström exponent between 355 and 532nm) is 0.10±0.02(1.2±0.19), and the lidar ratio at 532nm (43±7sr) is lower than that of typical urban pollution aerosol, which is probably affected by hygroscopic growth of water-soluble aerosolssuch as nitrate or the formation of secondary organic aerosols. In the polluted dust episode, the depolarization ratio (Ångström exponent) is 0.19±0.03 (1.0±0.35), and the lidar ratio is 51±7sr. In the pure dust episode, compared with the former, the depolarization ratio (0.25±0.03) is larger, the Ångström exponent (0.11±0.44) is smaller, and the lidar ratio is 40±4sr.