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Elementa (Wash D C)

Title:		Factors controlling surface ozone in the Seoul Metropolitan Area during the KORUS-AQ campaign
Author(s):		Kim H; Gil J; Lee M; Jung J; Whitehill A; Szykman J; Lee G; Kim DS; Cho S; Ahn JY; Hong J; Park MS;
Address:		"Department of Earth and Environmental Sciences, Korea University, Seoul, KR. Center for Gas Analysis, Korea Research Institute of Standards and Science, Daejeon, KR. US EPA, Research Triangle Park, Durham, NC, US. Department of Environmental Sciences, Hankuk University of Foreign Studies, Yongin, KR. Department of Environmental Engineering, Kunsan National University, Kunsan, KR. Seoul Metropolitan Government Research Institute of Public Health and Environment, Gyeonggi-do, KR. Department of Climate and Air Quality, National Institute of Environmental Research, Incheon, KR. Department of Atmospheric Sciences, Yonsei University, Seoul, KR. Research Center for Atmospheric Environment, Hankuk University of Foreign Sturdies, Yongin, KR"
Journal Title:		Elementa (Wash D C)
Year:		2020
Volume:		8
Issue:		46
Page Number:		-
DOI:		10.1525/elementa.444
ISSN/ISBN:		2325-1026 (Print) 2325-1026 (Electronic) 2325-1026 (Linking)
Abstract:		"To understand the characteristics of air quality in the Seoul Metropolitan Area, intensive measurements were conducted under the Korea-United States Air Quality (KORUS-AQ) campaign. Trace gases such as O(3), NO(x), NO(y), SO(2), CO, and volatile organic compounds (VOCs), photochemical byproducts such as H(2)O(2) and HCHO, aerosol species, and meteorological variables including planetary boundary layer height were simultaneously measured at Olympic Park in Seoul. During the measurement period, high O(3) episodes that exceeded the 90 ppbv hourly maximum occurred on 14 days under four distinct synoptic meteorological conditions. Furthermore, local circulation such as land-sea breeze and diurnal evolution of the boundary layer were crucial in determining the concentrations of precursor gases, including NO(x) and VOC as well as O(3). During such episodes, the nighttime NO(x) and VOC and daytime UV levels were higher compared to non-episode days. The overall precursor levels and photochemical activity were represented fairly well by variations in the HCHO, which peaked in the morning during the high O(3) episodes. This study revealed that toluene was the most abundant VOC in Seoul, and its concentration increased greatly with NO(x) due to the large local influence under stagnant conditions. When O(3) was highly elevated concurrently with PM(2.5) under dominant westerlies, NO(x) and VOCs were relatively lower and CO was noticeably higher than in other episodes. Additionally, the O(3) production efficiency was the highest due to a low NO(x) with the highest NO(z)/NO(y) ratio among the four episodes. When westerlies were dominant in transport-south episode, the nighttime concentration of O (3) remained as high as 40~50 ppbv due to the minimum level of NO(x) titration. Overall, the Seoul Metropolitan Area is at NO(x)-saturated and VOC-limited conditions, which was diagnosed by indicator species and VOC/NO(x) ratios"
Keywords:		Air quality Korus-aq NOx and VOCs Ozone Pm2.5 SMA (Seoul Metropolitan Area);
Notes:		"PubMed-not-MEDLINEKim, Heejeong Gil, Junsu Lee, Meehye Jung, Jinsang Whitehill, Andrew Szykman, James Lee, Gangwoong Kim, Deug-Soo Cho, Seogju Ahn, Jun-Young Hong, Jinkyu Park, Moon-Soo eng EPA999999/ImEPA/Intramural EPA/ 2020/01/01 Elementa (Wash D C). 2020; 8(46):10.1525/elementa.444. doi: 10.1525/elementa.444"