Meteorological and chemical factors controlling ozone formation in Seoul during MAPS-Seoul 2015

Heejeong Kim, Woo Chul Choi, Ho Jun Rhee, Inseon Suh, Meehye Lee, Donald R. Blake, Saewung Kim, Jinsang Jung, Gangwoong Lee, Deug Soo Kim, Seung Myung Park, Junyoung Ahn, Sang Deok Lee

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Abstract

To understand the chemical mechanisms of controlling factors in ozone (O3) formation in early summer in Seoul, a comprehensive study encompassing measurement and modeling was conducted under the Megacity Air Pollution Study-Seoul (MAPS-Seoul) campaign. From May 18 to June 12, 2015, O3 and peroxyacetyl nitrate (PAN) were measured, along with their precursors, including NOx and volatile organic compounds (VOCs), at the Korea Institute of Science and Technology, located in northeast Seoul. VOCs were sampled in a canister twice a day (at 09:30 and 15:00) and analyzed via gas chromatography. The meteorological conditions and chemical regimes of the air masses were clearly distinguished during the study period. In May, NOx concentrations were higher with more pronounced diurnal cycles of precursors and O3 under constant westerly winds. By contrast, stagnant conditions developed in June, which reduced the inflow of primary emissions from the downtown area but increased the influence from the neighboring forest under high temperatures. As a result, the ratio of O3 to odd oxygen was higher in June, indicating a less efficient removal of O3 by NOx. In the same context, the air mass was chemically more aged with a higher NO2/NOx ratio and enhanced OH reactivity of oxygenated and biogenic VOCs in June. The overall measurement results suggest that O3 formation is slightly more sensitive to VOCs than to NOx in Seoul during this season, when O3 concentrations are the highest of the year.

Original languageEnglish
Pages (from-to)2274-2286
Number of pages13
JournalAerosol and Air Quality Research
Volume18
Issue number9
DOIs
Publication statusPublished - 2018 Sep 1

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Keywords

  • MAPS-Seoul
  • Meteorological condition
  • NO
  • O formation
  • VOCs

ASJC Scopus subject areas

  • Environmental Chemistry
  • Pollution

Cite this

Kim, H., Choi, W. C., Rhee, H. J., Suh, I., Lee, M., Blake, D. R., Kim, S., Jung, J., Lee, G., Kim, D. S., Park, S. M., Ahn, J., & Lee, S. D. (2018). Meteorological and chemical factors controlling ozone formation in Seoul during MAPS-Seoul 2015. Aerosol and Air Quality Research, 18(9), 2274-2286. https://doi.org/10.4209/aaqr.2017.11.0445