title: OH reactivity in urban and suburban regions in Seoul, South Korea - an East Asian megacity in a rapid transition.
abstract: South Korea has recently achieved developed country status with the second largest megacity in the world, the Seoul Metropolitan Area (SMA). This study provides insights into future changes in air quality for rapidly emerging megacities in the East Asian region. We present total OH reactivity observations in the SMA conducted at an urban Seoul site (May-June, 2015) and a suburban forest site (Sep, 2015). The total OH reactivity in an urban site during the daytime was observed at similar levels (∼15 s(-1)) to those previously reported from other East Asian megacity studies. Trace gas observations indicate that OH reactivity is largely accounted for by NOX (∼50%) followed by volatile organic compounds (VOCs) (∼35%). Isoprene accounts for a substantial fraction of OH reactivity among the comprehensive VOC observational dataset (25-47%). In general, observed total OH reactivity can be accounted for by the observed trace gas dataset. However, observed total OH reactivity in the suburban forest area cannot be largely accounted for (∼70%) by the trace gas measurements. The importance of biogenic VOC (BVOCs) emissions and oxidations used to evaluate the impacts of East Asian megacity outflows for the regional air quality and climate contexts are highlighted in this study.
authors.affiliation: Department of Earth System Science, University of California, Irvine, Irvine CA 92697, USA. saewungk@uci.edu.
authors.forename: Saewung
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Earth System Science, University of California, Irvine, Irvine CA 92697, USA. saewungk@uci.edu.
authors.forename: Dianne
authors.initials: D
authors.lastname: Sanchez
authors.affiliation: Department of Earth System Science, University of California, Irvine, Irvine CA 92697, USA. saewungk@uci.edu.
authors.forename: Mark
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Earth System Science, University of California, Irvine, Irvine CA 92697, USA. saewungk@uci.edu.
authors.forename: Roger
authors.initials: R
authors.lastname: Seco
authors.affiliation: Department of Earth System Science, University of California, Irvine, Irvine CA 92697, USA. saewungk@uci.edu.
authors.forename: Daun
authors.initials: D
authors.lastname: Jeong
authors.affiliation: Department of Chemistry, University of California, Irvine, Irvine CA 92697, USA.
authors.forename: Stacey
authors.initials: S
authors.lastname: Hughes
authors.affiliation: Department of Chemistry, University of California, Irvine, Irvine CA 92697, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Barletta
authors.affiliation: Department of Chemistry, University of California, Irvine, Irvine CA 92697, USA.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Blake
authors.affiliation: The Division of Metrology for Quality of Life, Korea Research Institute of Standards and Science, Daejeon, South Korea 34113.
authors.forename: Jinsang
authors.initials: J
authors.lastname: Jung
authors.affiliation: Department of Environmental Engineering, Kunsan National University, Kunsan, South Korea 573-701.
authors.forename: Deugsoo
authors.initials: D
authors.lastname: Kim
authors.affiliation: Department of Environmental Sciences, Hankuk University of Foreign Studies, Yongin, South Korea 449-791.
authors.forename: Gangwoong
authors.initials: G
authors.lastname: Lee
authors.affiliation: Department of Earth and Environmental Sciences, Korea University, Seoul, South Korea 02841.
authors.forename: Meehye
authors.initials: M
authors.lastname: Lee
authors.affiliation: Department of Climate and Air Quality, National Institute of Environmental Research, Incheon, South Korea 22689.
authors.forename: Joonyoung
authors.initials: J
authors.lastname: Ahn
authors.affiliation: Department of Climate and Air Quality, National Institute of Environmental Research, Incheon, South Korea 22689.
authors.forename: Sang-Deok
authors.initials: SD
authors.lastname: Lee
authors.affiliation: Department of Climate and Air Quality, National Institute of Environmental Research, Incheon, South Korea 22689.
authors.forename: Gangnam
authors.initials: G
authors.lastname: Cho
authors.affiliation: Department of Climate and Air Quality, National Institute of Environmental Research, Incheon, South Korea 22689.
authors.forename: Min-Young
authors.initials: MY
authors.lastname: Sung
authors.affiliation: Department of Climate and Air Quality, National Institute of Environmental Research, Incheon, South Korea 22689.
authors.forename: Yong-Hwan
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Department of Climate and Air Quality, National Institute of Environmental Research, Incheon, South Korea 22689.
authors.forename: Dan Bi
authors.initials: DB
authors.lastname: Kim
authors.affiliation: Division of Interdisciplinary Studies, Konkuk University, Seoul, South Korea 05025.
authors.forename: Younha
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Division of Interdisciplinary Studies, Konkuk University, Seoul, South Korea 05025.
authors.forename: Jung-Hun
authors.initials: JH
authors.lastname: Woo
authors.affiliation: School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea 08826.
authors.forename: Duseong
authors.initials: D
authors.lastname: Jo
authors.affiliation: School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea 08826.
authors.forename: Rokjin
authors.initials: R
authors.lastname: Park
authors.affiliation: Department of Climate and Air Quality, National Institute of Environmental Research, Incheon, South Korea 22689.
authors.forename: Jeong-Hoo
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Climate and Air Quality, National Institute of Environmental Research, Incheon, South Korea 22689.
authors.forename: You-Deog
authors.initials: YD
authors.lastname: Hong
authors.affiliation: Department of Climate and Air Quality, National Institute of Environmental Research, Incheon, South Korea 22689.
authors.forename: Ji-Hyung
authors.initials: JH
authors.lastname: Hong