Aerosols
; Air quality
; Atmospheric movements
; Emission control
; Optical radar
; Quality control
; Sulfur
; Sulfur dioxide
; Wind
; APEC
; Beijing
; Haze
; Regional transport
; Southwest pathway
; Backscattering
; sulfur dioxide
; aerosol
; air mass
; air quality
; backscatter
; emission control
; formation mechanism
; haze
; lidar
; particle size
; size distribution
; sulfur dioxide
; vertical profile
; wind velocity
; aerosol
; air pollutant
; air pollution control
; Article
; atmospheric pressure
; China
; environmental parameters
; haze
; meteorology
; motor vehicle
; optical depth
; particle size
; priority journal
; validation study
; velocity
; wind
; Beijing [China]
; China
Scopus学科分类:
Environmental Science: Water Science and Technology
; Earth and Planetary Sciences: Earth-Surface Processes
; Environmental Science: Environmental Chemistry
英文摘要:
During the 2014 Asia-Pacific Economic Cooperation (APEC) conference period, Beijing's air quality was greatly improved as a result of a series of tough emission control measures being implemented in Beijing and its surrounding provinces. However, a moderate haze occurred during the period of 4–5 November. In order to evaluate the emission control measures and study the formation mechanism of the haze, a comprehensive field observation based on a supersite and a lidar network was carried out from 25 October 2014 to 20 January 2015. By investigating the variations in aerosol number concentration and mean backscattering coefficient before, during and after the APEC period, it was found that number concentration of accumulation mode and coarse mode particles experienced the most significant decrease by 47% and 68%, and mean backscattering coefficient below 1 km decreased by 34% during the APEC period. Being characterized as “rapidly accumulating and rapidly dispersing”, the moderate haze occurred during the APEC period was probably initiated by a wind direction change to south and an increase of wind speed to 4 m/s. Sulfur dioxide involved plume nucleation without growth in size as well as a burst of particles ranging between 100 and 300 nm were observed simultaneously during the haze episode. The elevation of sulfur dioxide concentration and particle number concentration was highly correlated with the southerly wind, signifying the contribution of regional transport. It was observed by the lidar network that the aerosol backscattering coefficient increased in sequence among three sites along the southwest pathway, suggesting that aerosols might be transported from the southwest to the northeast of Beijing with a speed of approximately 17 km/h, which agreed with the movement of air masses modeled by Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT). The dual-wavelength lidar (355 and 532 nm) observation suggested that transportation of fine particles from high-level atmosphere (approximately 2 km) could be the potential sources of the haze. Our result showed that regional transport would contribute to haze formation in Beijing under such meteorological conditions, thus, to maintain the “APEC blue”, significant attention should be paid to controlling regional transport through the southwest pathway. � 2016 Elsevier Ltd
Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, China; CAS Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China; Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China; Advanced Propulsion Laboratory, Department of Modern Mechanics, University of Science and Technology of China, Hefei, China
Recommended Citation:
Zhang J,, Chen Z,, Lu Y,et al. Characteristics of aerosol size distribution and vertical backscattering coefficient profile during 2014 APEC in Beijing[J]. Atmospheric Environment,2017-01-01,148