title: Mechanism for the formation and microphysical characteristics of submicron aerosol during heavy haze pollution episode in the Yangtze River Delta, China.
abstract: In this paper we investigate a severe pollution episode that occurred in the Yangtze River Delta (YRD) region in January 2013. The episode was caused by the combination of anthropogenic emissions and unusual atmospheric circulation, the depression of strong cold air activities and the very unfavorable dispersion. The episode contained three haze events (haze1: Jan. 4-9, haze2: Jan. 10-13, and haze3: Jan. 14-16). In Nanjing, aerosol size distributions from 10nm to 10 μm and chemical components of single particles from 0.2 to 2 μm were measured with a Wide Range Particle Spectrometer (WPS) and a Single Particle Aerosol Mass Spectrometer (SPAMS), respectively. The results indicate that the mean PM2.5 concentrations in the YRD region were greater than 110 μg·m(-3). The highest PM2.5 concentration of 175.6 μg·m(-3) occurred in Nanjing; the other cities had values in the range of 110.8-147.3 μg·m(-3). The average PM2.5 concentrations were 58.3, 122.7, 145.4 and 154.7 μg·m(-3) on clean and haze1, haze2 and haze3 days, respectively. The highest PM2.5 values of 416.5, 415.5 and 300.5 μg·m(-3) in Nanjing occurred during the three haze events. The spectra of the aerosol number concentrations had unimodal distributions on clean and haze days. The maximum surface area peaks were located at 0.5-0.7 μm and had values of 419, 1397, 1309 and 1378 μm(2)·cm(-3)·nm(-1) on clean and haze1, haze2 and haze3 days, respectively. The number concentrations of biomass/biofuel burning-containing particles (biomass), organic carbon-containing particles (OC), elemental carbon-containing particles (EC), nitrate-containing particles (nitrate) and sulfate-containing particles (sulfate) increased significantly during the haze events. The chemical components of the aerosols during the haze1 and haze2 events were similar to those on clean days, and variations were caused by local particle accumulations under poor diffusion conditions. The high EC particle concentration of 24.76% during the haze3 event was impacted by the pollutants transported from surrounding cities. In addition, the different chemical components showed distinct size distributions.
authors.affiliation: Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China.
authors.forename: Honglei
authors.initials: H
authors.lastname: Wang
authors.affiliation: Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China. Electronic address: junlinan@nuist.edu.cn.
authors.forename: Junlin
authors.initials: J
authors.lastname: An
authors.affiliation: Jiaxing Environmental Monitoring Station, Jiaxing 314000, China.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Shen
authors.affiliation: Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhu
authors.affiliation: Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Pan
authors.affiliation: State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institu te of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Zirui
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Liu
authors.affiliation: Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Duan
authors.affiliation: Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institu te of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Yuesi
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000336:Aerosols / Q000032:analysis*; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data; D002681:China; D004784:Environmental Monitoring; D052638:Particulate Matter / Q000032:analysis*
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter
keywords: Aerosol number concentration; Haze; PM(2.5); SPAMS; The YRD region