title: Characterization and source identification of sub-micron particles at the HKUST Supersite in Hong Kong.
abstract: Particle size distribution measurements were conducted continuously at a 30-second interval using the Fast Mobility Particle Sizer (FMPS) in August, September, November and December of 2011 at a coastal background site in Hong Kong. Concurrent measurements of CO, NOx, O3, SO2 and volatile organic compounds (VOCs) were used to determine the causes of high particle number concentration (PNC) events. In all sampling months, PNC were usually higher in the evening, likely resulting from the arrival of upwind air pollutants as wind direction changed in the late afternoon. On the more polluted days, the PNC were usually higher around noon, particularly in August, similar to the diurnal trend of O3. The mode diameter at noon was smaller than in other time periods in all sampling months, further highlighting the role of secondary formation at this urban background site. A prolonged period of pollution episode occurred in late August. High PNC resulted from the arrival of pollution laden air from the PRD region or super regions. In December, new particle formation followed by subsequent growth accounted for most of the polluted days. Overall, meteorology was the most important parameter affecting particle concentrations and formation at this Hong Kong background site.
authors.affiliation: Air Quality Studies, Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hong Kong, China.
authors.forename: K
authors.initials: K
authors.lastname: Cheung
authors.affiliation: Air Quality Studies, Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hong Kong, China; Department of Atmospheric Sciences, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, China.
authors.forename: Z H
authors.initials: ZH
authors.lastname: Ling
authors.affiliation: Air Quality Studies, Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hong Kong, China.
authors.forename: D W
authors.initials: DW
authors.lastname: Wang
authors.affiliation: Air Quality Studies, Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hong Kong, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Air Quality Studies, Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hong Kong, China. Electronic address: hai.guo@polyu.edu.hk.
authors.forename: H
authors.initials: H
authors.lastname: Guo
authors.affiliation: Division of Environment, Hong Kong University of Science and Technology, Hong Kong, China.
authors.forename: B
authors.initials: B
authors.lastname: Lee
authors.affiliation: Division of Environment, Hong Kong University of Science and Technology, Hong Kong, China.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Li
authors.affiliation: Division of Environment, Hong Kong University of Science and Technology, Hong Kong, China; Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Hong Kong, China. Electronic address: keckchan@ust.hk.
authors.forename: C K
authors.initials: CK
authors.lastname: Chan
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data*; D004784:Environmental Monitoring; D006723:Hong Kong; D055904:Meteorology; D052638:Particulate Matter / Q000032:analysis*; D055549:Volatile Organic Compounds / Q000032:analysis; D014919:Wind
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D055549:Volatile Organic Compounds
keywords: FMPS; New particle formation; PNC; Sub-micron particles