ALBERT

Description: [1]  We present combined Raman and elastic backscatter lidar observations that were carried out in Zhongshan, PRD (Pearl River Delta), China, during two periods in 2009: one haze pollution period and one moderate pollution period. During the haze period , high AOD (0.86 and 1.20 at 355 nm) and medium Ångström exponents (1.23 and 1.35 at 355 nm/532 nm) were observed. In the moderate pollution period, the corresponding parameters were comparatively lower with values of 0.83 and 0.74 at 355 nm for AOD and 1.108 and 0.98 at 355 nm/532 nm for Ångström exponent.The mean lidar ratios in the two periods were 64 ± 10sr and 56 ±9 sr, respectively, at 355 nm. The lidar ratio during haze phase was a bit higher compared to that in previous observations in this area. The calculated values of the lidar ratio and Ångström exponent were also used to help identify aerosol types. The Ångström exponent was calculated for the extinction from the wavelength pair 355 nm/532 nm, with high values of around 1.35 for the haze event. The particle size distribution (PSD) and single scattering albedo (SSA) derived from sunphotometer measurements indicate the presence of rather small particles. The three-day back trajectories from a HYSPLIT model in the haze period indicate that the air masses in the lower layer were advected from the southeast coast of China, where incomplete combustion of carbonaceous fuels and straw burning are frequently found in Shanghai during the heating period in winter. In the moderate pollution period, the air mass passed through western China, indicating a combination of some pollution from South Asia in case of strong convection, local aerosol aging, and smoke from adjacent fire burning spots in the PRD region.