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Boundary layer versus free tropospheric submicron particle formation: A case study from NASA DC-8 observations in the Asian continental outflow during the KORUS-AQ campaign

Park, Do-Hyeon and Cho, Chaeyoon and Kim, Hyeonmin and Park, Rokjin J. and Anderson, Bruce and Lee, Taehyoung and Huey, Greg L. and Wennberg, Paul O. and Weinheimer, Andrew J. and Yum, Seong Soo and Long, Russell and Kim, Sang-Woo (2021) Boundary layer versus free tropospheric submicron particle formation: A case study from NASA DC-8 observations in the Asian continental outflow during the KORUS-AQ campaign. Atmospheric Research, 264 . Art. No. 105857. ISSN 0169-8095. doi:10.1016/j.atmosres.2021.105857. https://resolver.caltech.edu/CaltechAUTHORS:20211102-201741089

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Abstract

In this study, we contrasted major secondary inorganic species and processes responsible for submicron particle formation (SPF) events in the boundary layer (BL) and free troposphere (FT) over the Korean Peninsula during Korea-United States Air Quality (KORUS-AQ) campaign (May–June 2016) using aircraft observations. The number concentration of ultrafine particles with diameters between 3 nm and 10 nm (N_(CN3–10)) during the entire KORUS-AQ period reached a peak (7606 ± 12,003 cm⁻³) at below 1 km altitude, implying that the particle formation around the Korean Peninsula primarily occurred in the daytime BL. During the BL SPF case (7 May 2016), the SPF over Seoul metropolitan area was more attributable to oxidation of NO₂ rather than SO₂-to-sulfate conversion. From the analysis of the relationship between nitrogen oxidation ratio (NOR) and temperature or relative humidity (RH), NOR showed a positive correlation only with temperature. This suggests that homogeneous gas-phase reactions of NO₂ with OH or O₃ contributed to nitrate formation. From the relationship between N_(CN3–10) (> 10,000 cm⁻³) and the NOR (or sulfur oxidation ratio) at Olympic Park in Seoul during the entire KORUS-AQ period, it was regarded that the relative importance of nitrogen oxidation was grown as the N_(CN3–10) increased. During the FT SPF case (31 May 2016) over the yellow sea, the SO₂-to-sulfate conversion seemed to influence SPF highly. The sulfate/CO ratio had a positive correlation with both the temperature and RH, suggesting that aqueous-phase pathways as well as gas-phase reactions might be attributable to sulfate formation in the FT. In particular, FT SPF event on 31 May was possibly caused by the direct transport of SO₂ precursors from the continent above the shallow marine boundary layer under favorable conditions for FT SPF events, such as decreased aerosol surface area and increased solar radiation.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.atmosres.2021.105857DOIArticle
ORCID:
AuthorORCID
Wennberg, Paul O.0000-0002-6126-3854
Weinheimer, Andrew J.0000-0001-6175-8286
Additional Information:© 2021 Elsevier B.V. Received 13 May 2021, Revised 14 September 2021, Accepted 14 September 2021, Available online 16 September 2021. The authors are grateful to the NASA DC-8 pilots and crew, and to all members of the KORUS-AQ science team for their contributions during the field campaign and the agencies operating the surface networks. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT)(No. NRF-2021R1A4A5032320). Declaration of Competing Interest: None.
Funders:
Funding AgencyGrant Number
National Research Foundation of KoreaNRF-2021R1A4A5032320
Subject Keywords:Submicron particle formation; Secondary inorganic aerosols; Boundary layer; Free troposphere; KORUS-AQ
DOI:10.1016/j.atmosres.2021.105857
Record Number:CaltechAUTHORS:20211102-201741089
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20211102-201741089
Official Citation:Do-Hyeon Park, Chaeyoon Cho, Hyeonmin Kim, Rokjin J. Park, Bruce Anderson, Taehyoung Lee, Greg L. Huey, Paul O. Wennberg, Andrew J. Weinheimer, Seong Soo Yum, Russell Long, Sang-Woo Kim, Boundary layer versus free tropospheric submicron particle formation: A case study from NASA DC-8 observations in the Asian continental outflow during the KORUS-AQ campaign, Atmospheric Research, Volume 264, 2021, 105857, ISSN 0169-8095, https://doi.org/10.1016/j.atmosres.2021.105857.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111714
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:02 Nov 2021 21:13
Last Modified:02 Nov 2021 21:13

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