AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Vertical Profiles of Air Pollutants in Urban Boundary Layer: Results from the Measurements on Beijing 325m Meteorological Tower in Severe Haze Episodes
QINGQING WANG, Weiqi Xu, Wei Du, Chen Chen, Tingting Han, Dongsheng Ji, Zifa Wang, Yele Sun, Inst. of Atmospheric Physics, Chinese Academy of Sciences
Abstract Number: 419 Working Group: Urban Aerosols
Abstract The formation of severe haze episodes interacts closely with urban boundary layer (UBL), however, it is a great challenge for air quality models to precisely predict these events on the basis of known parameterization. One reason is the lack of understanding of the vertical evolution mechanisms of air pollutants within UBL. Thus, studying vertical distributions of air pollutants is essential to help elucidate the mechanisms of haze formation in megacity in China, and realize precise forecast of serious haze incidents. Here, vertical profiles of air pollution were measured with a container equipped on Beijing 325 m meteorological tower between ground level and 260m using Cavity Attenuated Phase Shift Particulate Matter extinction monitor (CAPS-PMext), CAPS-NO2 monitor, and Aethalometer. Submicron aerosol chemical species were synchronously measured in real-time at ground level and 260m with Aerodyne Aerosol Mass Spectrometer and Aerosol Chemical Speciation Monitor, respectively. Meteorological variables and lidar measurements were also obtained to help explain vertical evolution mechanisms of air pollutants. Vertical profiles of air pollutants were classified into four categories: (1) Well mixed. It usually happened when mixed-layer height or sable UBL height was higher than the pod slipping height, and no temperature inversion appeared; (2) Higher at the ground level. It usually happened when the local ground emission accumulated fast. Such pollutants vertical profile usually appeared in Beijing due to its strong emission capacity; (3) Higher at the 260m. It usually caused by the enhanced pollutants transport at the high altitude; (4) Significant transition at a certain height. It usually occurred when the UBL height was below the observation height of the slipping pod.