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Secondary organic aerosol production from local emissions dominates the organic aerosol budget over Seoul, South Korea, during KORUS-AQ

Nault, Benjamin A. and Campuzano-Jost, Pedro and Day, Douglas A. and Schroder, Jason C. and Anderson, Bruce and Beyersdorf, Andreas J. and Blake, Donald R. and Brune, William H. and Choi, Yonghoon and Corr, Chelsea A. and de Gouw, Joost A. and Dibb, Jack and DiGangi, Joshua P. and Diskin, Glenn S. and Fried, Alan and Huey, L. Gregory and Kim, Michelle J. and Knote, Christoph J. and Lamb, Kara D. and Lee, Taehyoung and Park, Taehyun and Pusede, Sally E. and Scheuer, Eric and Thornhill, Kenneth L. and Woo, Jung-Hun and Jimenez, Jose L. (2018) Secondary organic aerosol production from local emissions dominates the organic aerosol budget over Seoul, South Korea, during KORUS-AQ. Atmospheric Chemistry and Physics, 18 (24). pp. 17769-17800. ISSN 1680-7324.

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Organic aerosol (OA) is an important fraction of submicron aerosols. However, it is challenging to predict and attribute the specific organic compounds and sources that lead to observed OA loadings, largely due to contributions from secondary production. This is especially true for megacities surrounded by numerous regional sources that create an OA background. Here, we utilize in situ gas and aerosol observations collected on board the NASA DC-8 during the NASA–NIER KORUS-AQ (Korea–United States Air Quality) campaign to investigate the sources and hydrocarbon precursors that led to the secondary OA (SOA) production observed over Seoul. First, we investigate the contribution of transported OA to total loadings observed over Seoul by using observations over the Yellow Sea coupled to FLEXPART Lagrangian simulations. During KORUS-AQ, the average OA loading advected into Seoul was ∼1–3 µg sm^(−3). Second, taking this background into account, the dilution-corrected SOA concentration observed over Seoul was ∼140 µgsm^(−3) ppmv^(−1) at 0.5 equivalent photochemical days. This value is at the high end of what has been observed in other megacities around the world (20–70 µgsm^(−30) ppmv^(−1) at 0.5 equivalent days). For the average OA concentration observed over Seoul (13 µg sm^(−3)), it is clear that production of SOA from locally emitted precursors is the major source in the region. The importance of local SOA production was supported by the following observations. (1) FLEXPART source contribution calculations indicate any hydrocarbons with a lifetime of less than 1 day, which are shown to dominate the observed SOA production, mainly originate from South Korea. (2) SOA correlated strongly with other secondary photochemical species, including short-lived species (formaldehyde, peroxy acetyl nitrate, sum of acyl peroxy nitrates, dihydroxytoluene, and nitrate aerosol). (3) Results from an airborne oxidation flow reactor (OFR), flown for the first time, show a factor of 4.5 increase in potential SOA concentrations over Seoul versus over the Yellow Sea, a region where background air masses that are advected into Seoul can be measured. (4) Box model simulations reproduce SOA observed over Seoul within 11 % on average and suggest that short-lived hydrocarbons (i.e., xylenes, trimethylbenzenes, and semi-volatile and intermediate-volatility compounds) were the main SOA precursors over Seoul. Toluene alone contributes 9 % of the modeled SOA over Seoul. Finally, along with these results, we use the metric ΔOA/ΔCO_2 to examine the amount of OA produced per fuel consumed in a megacity, which shows less variability across the world than ΔOA∕ΔCO.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Nault, Benjamin A.0000-0001-9464-4787
Campuzano-Jost, Pedro0000-0003-3930-010X
Day, Douglas A.0000-0003-3213-4233
Beyersdorf, Andreas J.0000-0002-4496-2557
Brune, William H.0000-0002-1609-4051
Choi, Yonghoon0000-0001-6529-4722
de Gouw, Joost A.0000-0002-0385-1826
DiGangi, Joshua P.0000-0002-6764-8624
Diskin, Glenn S.0000-0002-3617-0269
Huey, L. Gregory0000-0002-0518-7690
Kim, Michelle J.0000-0002-4922-4334
Jimenez, Jose L.0000-0001-6203-1847
Additional Information:© Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. Received: 09 Aug 2018 – Discussion started: 24 Aug 2018 – Revised: 17 Nov 2018 – Accepted: 29 Nov 2018 – Published: 14 Dec 2018. This study was supported by NASA grants NNX15AT96G & 80NSSC18K0630 and EPA STAR 83587701-0. It has not been formally reviewed by the EPA. Michelle J. Kim was funded by NSF award number 1524860. Joost A. de Gouw worked as a part-time consultant for Aerodyne Research Inc. during the preparation phase of this paper. The authors acknowledge Joshua Schwarz and Anne Perring for the use of their black carbon data, Ronald Cohen, Paul Wooldridge, and Paul Romer for use of their ΣRONO_2 and ΣROONO_2 data, Paul Wennberg and John Crounse for the use of their HCN, DHT, and HNO_3 data, Armin Wisthaler for the use of their PTR-MS data, and Andrew Weinheimer and Denise Montzka for the use of their O_3, NO_x, and NO_y data. Finally, the authors acknowledge the NOAA ESRL GMD CCGG for the use of the CO measurements in Mongolia and China for the background measurements. Author contributions. BAN, PCJ, DAD, JCS, and JLJ collected the AMS data. BA, AJB, CAC, and KLT collected the data from LARGE. DRB collected the WAS data. WHB collected the OH, HO_2, and OHR data. YC and JPDG collected the CO measurements from the Picarro instrument. JD and ES collected MC/IC and filter measurements. GSD and SEP collected H2_O and ambient CO measurements. AF collected CH_2O measurements. LGH collected PAN, PPN, and SO_2 measurements. MJK collected HNO_3, DHT, and HCN measurements. CJK ran the FLEXPART analysis. KDL collected the BC measurements. TL and TP collected the KAMS data. JHW provided the emissions for the FLEXPART analysis. JAdG assisted in the analysis of the photochemical clocks and SOA production. BAN and JLJ prepared the original paper, and all authors contributed to the review and editing of the paper. Data availability. Measurements and FLEXPART results from the KORUS-AQ campaign are available at, last access: 16 February 2018. Measurements for the CO background are available at, last access: 22 November 2016. Supplement. The supplement related to this article is available online at: The authors declare that they have no conflict of interest. Disclaimer. The views expressed in this document are solely those of the authors and do not necessarily reflect those of the U.S. EPA. The EPA does not endorse any products or commercial services mentioned in this publication. Edited by: Robert McLaren. Reviewed by: two anonymous referees.
Funding AgencyGrant Number
Environmental Protection Agency (EPA)83587701-0
Record Number:CaltechAUTHORS:20190104-094928379
Persistent URL:
Official Citation:Nault, B. A., Campuzano-Jost, P., Day, D. A., Schroder, J. C., Anderson, B., Beyersdorf, A. J., Blake, D. R., Brune, W. H., Choi, Y., Corr, C. A., de Gouw, J. A., Dibb, J., DiGangi, J. P., Diskin, G. S., Fried, A., Huey, L. G., Kim, M. J., Knote, C. J., Lamb, K. D., Lee, T., Park, T., Pusede, S. E., Scheuer, E., Thornhill, K. L., Woo, J.-H., and Jimenez, J. L.: Secondary organic aerosol production from local emissions dominates the organic aerosol budget over Seoul, South Korea, during KORUS-AQ, Atmos. Chem. Phys., 18, 17769-17800,, 2018.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92091
Deposited By: George Porter
Deposited On:04 Jan 2019 23:43
Last Modified:04 Jan 2019 23:43

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