Columnar Optical Depth and Vertical Distribution of Aerosols over Shanghai

The vertical distributions and optical properties of aerosols over Shanghai were analyzed using data from ground-based observation, space remote sensing and trajectories. Measurements of spectral aerosol optical depth (AOD) were carried out at Shanghai using a hand-held multi-band sun photometer MICROTOPS II from November 2009 to October 2010. AODs were almost in low level during the entire experiment, especially in the period of the World Exhibition/Exposition (EXPO) 2010. And, the daily-averaged AODs showed a clear pattern of seasonal variation, with maximum 0.69 in November and minimum 0.24 in August. Angstrom exponents were commonly exceeding 1.30, indicating that fine particles mainly contributed to aerosol loading except springtime. Based on Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation/Cloud-Aerosol Lidar with Orthogonal Polarization (CALIPSO/CALIOP) retrieval and air back-trajectory modeling, the vertical distribution of aerosols were examined and classified into near-surface, mixed and multilayer transport types. The results denote the effects of aerosols from local sources or/and transported from remote sources on aerosol loadings. Comparison of AODs derived from CALIOP with those from ground observation revealed a reliable agreement with a correlative coefficient of 0.59. The variety of the aerosol types of Shanghai probably is the main contributor of the uncertainties.