AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Vertical Profiles of Aerosol Optical Properties and NO$_2 during two Severe Haze Episodes in Beijing
QINGQING WANG, Wei Du, Chen Chen, Weiqi Xu, Tingting Han, Dongsheng Ji, Zifa Wang, Yele Sun, Inst. of Atmospheric Physics, Chinese Academy of Sciences
Abstract Number: 167 Working Group: Haze in China: Sources, Formation Mechanisms, and Current Challenges
Abstract The formation of severe haze episodes interacts closely with atmospheric boundary layer (ABL). However, our knowledge of vertical profiles of aerosol characteristics and gas precursors in urban Beijing is rather limited. Here we report the results from two vertical experiments that were conducted from Nov. 19$^(th) to 21$^(st), 2014, and Jan. 12$^(th) to 16$^(th), 2015, at an urban site in Beijing. The vertical profiles of particle extinction, absorption, and gaseous NO$_2 from ground surface to 260 m were measured by a Cavity Attenuated Phase Shift (CAPS) extinction monitor, an Aethalometer, and a CAPS NO$_2 monitor, respectively. Collocated measurements of submicron aerosol composition (organics, sulfate, nitrate, ammonium, and chloride) were also carried out at ground surface with a high-resolution time-of-flight aerosol mass spectrometer and 260 m on the Beijing 325 m meteorological tower with an aerosol chemical speciation monitor. We observed very dynamic vertical evolution of aerosol optical properties and NO$_2 during the two severe haze episodes indicating a complex vertical mixing process and aerosol chemistry in the ABL. The vertical profiles of aerosol and gaseous were also found to interact closely with those of meteorological variables. Based on the vertical profiles from the two experiments, a concept framework describing the vertical evolution of ABL and its interactions with air pollution in Beijing was established. There are two special heights, the height of ABL and the height of the surface aerosol layer. Air pollution usually has significant differences at the height of the surface aerosol layer and the height of ABL respectively during daytime and nighttime.