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Park DH, Kim JE, Park JS, Choi JS, Kim SW. Impacts of the COVID-19 lockdown in China on new particle formation and particle number size distribution in three regional background sites in Asian continental outflow. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 858:159904. [PMID: 36328264 PMCID: PMC9622020 DOI: 10.1016/j.scitotenv.2022.159904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 10/24/2022] [Accepted: 10/29/2022] [Indexed: 06/16/2023]
Abstract
Despite the curtailment of atmospheric condensing precursor gases during the Coronavirus disease 2019 (COVID-19) lockdown (LD) period, unexpected haze events via the formation of new particles and their subsequent growth have been identified. This study investigated the impact of emission reduction during the Chinese LD period on the new particle formation (NPF) frequency and corresponding particle number size distribution (PNSD) at three regional background atmospheric monitoring sites in the western coastal areas of the Korean Peninsula. During this duration, the number concentrations of the nucleation- (<25 nm) and accumulation-mode (>90 nm) particles significantly decreased in Baengryeong (BRY), showing decreases of 34% and 29%, respectively. Unlike BRY, the PNSD in Anmyeon (AMY), which is influenced by nearby industrial emissions, remained nearly unchanged during the LD period, possibly because the reduction in industrial emissions was not significant during the social distancing period enforced by Korea. Bongseong (BOS) showed a similar variation to that of BRY; however, the magnitude of the reduction was weaker because of its higher altitude compared to other sites. The cyclostationary empirical orthogonal function technique was applied to the measured PNSDs at the three sites to objectively classify NPF events. Because mode 1 of cyclostationary loading vectors commonly represented the typical diurnal variation of PNSD during regional NPF events at three sites, mode 1 of the corresponding principal component time series was used for NPF classification. The NPF frequency decreased by 7%, 1%, and 7% in BRY, AMY, and BOS, respectively, despite favorable meteorological conditions, such as increased temperature and insolation during the LD period. The diurnal variation in the sulfuric acid (H2SO4) proxy implied that the H2SO4 proxy acted as a determining factor for NPF events during the NPF occurrence time (8-12 local hours) in AMY and BOS; however, NPF occurrence in BRY was not connected to the H2SO4 proxy level. This suggests that BRY was more likely to be influenced by the reduction in organic species in the continental upwind regions, while the occurrence of NPF events in AMY and BOS can be suppressed in association with the distinct reduction in inorganic compounds represented by the H2SO4 proxy during the LD period.
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Affiliation(s)
- Do-Hyeon Park
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Jeong Eun Kim
- Climate Research Department, National Institute of Meteorological Sciences, Seogwipo, Republic of Korea
| | - Jin-Soo Park
- Climate & Air Quality Research Department, National Institute of Environmental Research, Incheon 22689, Republic of Korea
| | - Jin-Soo Choi
- Climate & Air Quality Research Department, National Institute of Environmental Research, Incheon 22689, Republic of Korea
| | - Sang-Woo Kim
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea.
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2
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Lim S, Lee M, Yoo HJ. Size distributions, mixing state, and morphology of refractory black carbon in an urban atmosphere of northeast Asia during summer. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 856:158436. [PMID: 36108842 DOI: 10.1016/j.scitotenv.2022.158436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 08/21/2022] [Accepted: 08/28/2022] [Indexed: 06/15/2023]
Abstract
Black carbon (BC) exerts profound impacts on air quality, human health, and climate. Here, we investigated concentrations and size distributions of refractory BC (rBC) and mixing state and morphology of rBC-containing particles in urban Seoul for 2019 summer. Mass concentrations of rBC ranged from 0.02 μgm-3 to 2.89 μgm-3, and daily maximums of rBC mass, daily minimums of rBC mass median diameter (MMD) (110-130 nm), and shell-to-core ratio (Rshell/core) occurred with NO2 maximums during morning rush hour. As the first report of ground observations on rBC mixing state, these results indicate that vehicle emission is a major local source of rBC in Seoul. MMDs of 127-146 nm and the greatest mass loadings of ≥1 μg m-3 were accompanied by high O3 and PM2.5 concentrations, in contrast to the largest MMDs (135-165 nm) associated with transport from upstream regions. The average Rshell/core was 1.25 for the rBC mass-equivalent diameter (DrBC) of 140-220 nm. Rshell/core increased gradually through the day and was positively correlated with Ox concentration, indicating photochemical aging of rBC particles. Co-emissions of rBC and volatile organic compounds from vehicles facilitated internal mixing during the daytime. However, Rshell/core tended to be low at temperature >∼30 °C, while 58 % of rBC particles with Rshell/core exceeding 1.25 were found at nighttime under relative humidity >75 %. These results demonstrate that the mixing state of freshly-emitted rBC particles was altered through coating by photochemically oxidized vapors during the day and hygroscopic growth at night. Additionally, the delay-time approach revealed rBC morphological characteristics, the most common being the bare type (74 %), and the attached type (6 %) was relatively large in numbers during morning rush hour. Therefore, it is suggested that during summer, rBC particles from traffic emissions should be considered in parallel to winter pollution mitigation strategies in urban atmosphere of northeast Asia.
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Affiliation(s)
- Saehee Lim
- Dept. of Earth and Environmental Sciences, Korea University, Seoul 02841, Republic of Korea; Dept. of Environmental Engineering, Chungnam National University, Deajeon 34134, Republic of Korea
| | - Meehye Lee
- Dept. of Earth and Environmental Sciences, Korea University, Seoul 02841, Republic of Korea.
| | - Hee-Jung Yoo
- Climate Research Department, National Institute of Meteorological Sciences, Jeju 63568, Republic of Korea
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Length Scale Analyses of Background Error Covariances for EnKF and EnSRF Data Assimilation. ATMOSPHERE 2022. [DOI: 10.3390/atmos13020160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Data assimilation (DA) combines incomplete background values obtained via chemical transport model predictions with observational information. Several 3-Dimensional variational (3DVAR) and sequential methods (e.g., ensemble Kalman filter (EnKF)) are used to define model errors and build a background error covariance (BEC) and are important factors affecting the prediction performance of DA. The BEC determines the spatial range, where observation concentration is reflected in the model when DA is applied to an air pollution transport model. However, studies investigating the characteristics of BEC using air quality models remain lacking. In this study, horizontal length scale (HLS) and vertical length scale (VLS) analyses of a BEC were applied to EnKF and ensemble square root filter (EnSRF), respectively, and two ensemble-based DA methods were performed; the characteristics were compared with those of a BEC applied to 3DVAR. The results of 6 h PM2.5 predictions performed for 42 days were evaluated for a control run without DA (CTR), 3DVAR, EnKF, and EnSRF. HLS and VLS respectively exhibited a high correlation with the ground wind speed and with the planetary boundary layer height for diurnal and daily variations; EnKF and EnSRF exhibited superior performances among all the methods. The root mean square errors were 11.9 μg m−3 and 11.7 μg m−3 for EnKF and EnSRF, respectively, while those for 3DVAR and CTR were 12.6 μg m−3 and 18.3 μg m−3, respectively. Thus, we proposed a simple method to find a Gaussian function that best described the error correlation of the BEC based on the physical distance.
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Kenagy HS, Romer Present PS, Wooldridge PJ, Nault BA, Campuzano-Jost P, Day DA, Jimenez JL, Zare A, Pye HOT, Yu J, Song CH, Blake DR, Woo JH, Kim Y, Cohen RC. Contribution of Organic Nitrates to Organic Aerosol over South Korea during KORUS-AQ. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:16326-16338. [PMID: 34870986 PMCID: PMC8759034 DOI: 10.1021/acs.est.1c05521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The role of anthropogenic NOx emissions in secondary organic aerosol (SOA) production is not fully understood but is important for understanding the contribution of emissions to air quality. Here, we examine the role of organic nitrates (RONO2) in SOA formation over the Korean Peninsula during the Korea-United States Air Quality field study in Spring 2016 as a model for RONO2 aerosol in cities worldwide. We use aircraft-based measurements of the particle phase and total (gas + particle) RONO2 to explore RONO2 phase partitioning. These measurements show that, on average, one-fourth of RONO2 are in the condensed phase, and we estimate that ≈15% of the organic aerosol (OA) mass can be attributed to RONO2. Furthermore, we observe that the fraction of RONO2 in the condensed phase increases with OA concentration, evidencing that equilibrium absorptive partitioning controls the RONO2 phase distribution. Lastly, we model RONO2 chemistry and phase partitioning in the Community Multiscale Air Quality modeling system. We find that known chemistry can account for one-third of the observed RONO2, but there is a large missing source of semivolatile, anthropogenically derived RONO2. We propose that this missing source may result from the oxidation of semi- and intermediate-volatility organic compounds and/or from anthropogenic molecules that undergo autoxidation or multiple generations of OH-initiated oxidation.
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Affiliation(s)
- Hannah S Kenagy
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Paul S Romer Present
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Paul J Wooldridge
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Benjamin A Nault
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Pedro Campuzano-Jost
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Douglas A Day
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Jose L Jimenez
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Azimeh Zare
- Department of Chemistry, University of California, Berkeley, California 94710, United States
| | - Havala O T Pye
- Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, Durham, North Carolina 27709, United States
| | - Jinhyeok Yu
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61105, Republic of Korea
| | - Chul H Song
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61105, Republic of Korea
| | - Donald R Blake
- Department of Chemistry, University of California, Irvine, California 92697, United States
| | - Jung-Hun Woo
- Department of Civil and Environmental Engineering, Konkuk University, Seoul 05029, Republic of Korea
| | - Younha Kim
- Energy, Climate, and Environment (ECE) Program, International Institute for Applied Systems Analysis (IIASA), Laxenburg A-2361, Austria
| | - Ronald C Cohen
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Department of Earth & Planetary Sciences, University of California, Berkeley CA 94 720, United States
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Park DH, Cho C, Kim H, Park RJ, Anderson B, Lee T, Huey GL, Wennberg PO, Weinheimer AJ, Yum SS, Long R, Kim SW. 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 2021; 264:1-11. [PMID: 36936135 PMCID: PMC10019524 DOI: 10.1016/j.atmosres.2021.105857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
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 (NCN3-10) during the entire KORUS-AQ period reached a peak (7,606 ± 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 NCN3-10 (> 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 NCN3-10 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.
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Affiliation(s)
- Do-Hyeon Park
- School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
| | - Chaeyoon Cho
- School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
| | - Hyeonmin Kim
- School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
| | - Rokjin J. Park
- School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
| | | | - Taehyoung Lee
- Department of Environmental Science, Hankuk University of Foreign Studies, Korea
| | - Greg L. Huey
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | | | | | - Seong Soo Yum
- Department of Atmosphere Science, Yonsei University, Seoul, Korea
| | - Russell Long
- Office of Research and Development, U.S. EPA, Research Triangle Park, NC, USA
| | - Sang-Woo Kim
- School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
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Park G, Kim K, Park T, Kang S, Ban J, Choi S, Yu DG, Lee S, Lim Y, Kim S, Mun S, Woo JH, Jeon CS, Lee T. Primary and secondary aerosols in small passenger vehicle emissions: Evaluation of engine technology, driving conditions, and regulatory standards. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 286:117195. [PMID: 33975218 DOI: 10.1016/j.envpol.2021.117195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 04/01/2021] [Accepted: 04/19/2021] [Indexed: 06/12/2023]
Abstract
The characteristics of primary gas/aerosol and secondary aerosol emissions were identified for small passenger vehicles using typical fuel types in South Korea (gasoline, liquefied petroleum gas (LPG), and diesel). The generation of secondary organic aerosol (SOA) was explored using the potential aerosol mass (PAM) oxidation flow reactor. The primary emissions did not vary significantly between fuel types, combustion technologies, or aftertreatment systems, while the amount of NH3 was higher in gasoline and LPG vehicle emissions than that in diesel vehicle emissions. The SOA emission factor was 11.7-66 mg kg-fuel-1 for gasoline vehicles, 2.4-50 mg kg-fuel-1 for non-diesel particulate filter (non-DPF) diesel vehicles (EURO 2-3), 0.4-40 mg kg-fuel-1 for DPF diesel vehicles (EURO 4-6), and 3-11 mg kg-fuel-1 for LPG vehicles (lowest). The carbonaceous aerosols (equivalent black carbon (eBC) + primary organic aerosol + SOA) of diesel vehicles in EURO 4-6 were reduced by up to 95% compared to those in EURO 2-3. The expected SOA yield increased through the hot-condition combustion section of a vehicle, over the SOA range of 0.2-155 μg m-3. These results provide the necessary data to analyze all types of SOA generated by the gas-phase oxidation in vehicle emissions in metropolitan areas.
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Affiliation(s)
- Gyutae Park
- Department of Environmental Science, Hankuk University of Foreign Studies, Yongin, 17035, South Korea
| | - Kyunghoon Kim
- Department of Environmental Science, Hankuk University of Foreign Studies, Yongin, 17035, South Korea
| | - Taehyun Park
- Department of Environmental Science, Hankuk University of Foreign Studies, Yongin, 17035, South Korea
| | - Seokwon Kang
- Department of Environmental Science, Hankuk University of Foreign Studies, Yongin, 17035, South Korea
| | - Jihee Ban
- Department of Environmental Science, Hankuk University of Foreign Studies, Yongin, 17035, South Korea
| | - Siyoung Choi
- Department of Environmental Science, Hankuk University of Foreign Studies, Yongin, 17035, South Korea
| | - Dong-Gil Yu
- Department of Environmental Science, Hankuk University of Foreign Studies, Yongin, 17035, South Korea
| | - Sanguk Lee
- Transportation Pollution Research Center, National Institute of Environmental Research, Incheon, 22689, South Korea
| | - Yunsung Lim
- Transportation Pollution Research Center, National Institute of Environmental Research, Incheon, 22689, South Korea
| | - Sunmoon Kim
- Transportation Pollution Research Center, National Institute of Environmental Research, Incheon, 22689, South Korea
| | - Sunhee Mun
- Transportation Pollution Research Center, National Institute of Environmental Research, Incheon, 22689, South Korea
| | - Jung-Hun Woo
- Department of Civil and Environmental Engineering, Konkuk University, Seoul, 05029, South Korea
| | - Chan-Soo Jeon
- Korea Institute of Civil Engineering and Building Technology, Goyang, 10223, South Korea
| | - Taehyoung Lee
- Department of Environmental Science, Hankuk University of Foreign Studies, Yongin, 17035, South Korea.
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7
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Cho C, Schwarz JP, Perring AE, Lamb KD, Kondo Y, Park JU, Park DH, Shim K, Park JS, Park RJ, Lee M, Song CK, Kim SW. Light-absorption enhancement of black carbon in the Asian outflow inferred from airborne SP2 and in-situ measurements during KORUS-AQ. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 773:145531. [PMID: 33582332 DOI: 10.1016/j.scitotenv.2021.145531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/21/2021] [Accepted: 01/26/2021] [Indexed: 06/12/2023]
Abstract
We investigated the changes in the size distribution, coating thickness, and mass absorption cross-section (MAC) of black carbon (BC) with aging and estimated the light absorption enhancement (Eabs) in the Asian outflow from airborne in-situ measurements during 2016 KORUS-AQ campaign. The BC number concentration decreased, but mass mean diameter increased with increasing altitude in the West Coast (WC) and Seoul Metropolitan Area (SMA), reflecting the contrast between freshly emitted BC-containing particles at the surface and more aged aerosol associated with aggregation during vertical mixing and transport. Contradistinctively, BC number and mass size distributions were relatively invariant with altitude over the Yellow Sea (YS) because sufficiently aged BC from eastern China were horizontally transported to all altitudes over the YS, and there are no significant sources at the surface. The averaged inferred MAC of refractory BC in three regions reflecting differences in their size distributions increased to 9.8 ± 1.0 m2 g-1 (YS), 9.3 ± 0.9 m2 g-1 (WC), and 8.2 ± 0.9 m2 g-1 (SMA) as BC coating thickness increased from 20 nm to 120 nm. The absorption coefficient of BC calculated from the coating thickness and MAC were highly correlated with the filter-based absorption measurements with the slope of 1.16 and R2 of 0.96 at 550 nm, revealing that the thickly coated BC had a large MAC and absorption coefficient. The Eabs due to the inferred coatings was estimated as 1.0-1.6, which was about 30% lower than those from climate models and laboratory experiments, suggesting that the increase in the BC absorption by the coatings in the Asian outflow is not as large as calculated in the previous studies. Organics contributed to the largest Eabs accounting for 69% (YS), 61% (WC), and 64% (SMA). This implies that organics are largely responsible for the lensing effect of BC rather than sulfates in the Asian outflow.
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Affiliation(s)
- Chaeyoon Cho
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Joshua P Schwarz
- NOAA Earth System Research Laboratory (ESRL), Chemical Sciences Division, Boulder, CO 80305, USA
| | - Anne E Perring
- NOAA Earth System Research Laboratory (ESRL), Chemical Sciences Division, Boulder, CO 80305, USA
| | - Kara D Lamb
- NOAA Earth System Research Laboratory (ESRL), Chemical Sciences Division, Boulder, CO 80305, USA; Cooperative Institute for Research in the Environmental Sciences (CIRES), University of Colorado, Boulder, CO 80309, USA
| | - Yutaka Kondo
- National Institute for Polar Research, Tachikawa, Tokyo 190-8518, Japan
| | - Jong-Uk Park
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Do-Hyeon Park
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Kyuseok Shim
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Jin-Soo Park
- National Institute of Environmental Research, Incheon 22689, Republic of Korea
| | - Rokjin J Park
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Meehye Lee
- Department of Earth and Environmental Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Chang-Keun Song
- School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Sang-Woo Kim
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea.
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Crawford JH, Ahn JY, Al-Saadi J, Chang L, Emmons LK, Kim J, Lee G, Park JH, Park RJ, Woo JH, Song CK, Hong JH, Hong YD, Lefer BL, Lee M, Lee T, Kim S, Min KE, Yum SS, Shin HJ, Kim YW, Choi JS, Park JS, Szykman JJ, Long RW, Jordan CE, Simpson IJ, Fried A, Dibb JE, Cho S, Kim YP. The Korea-United States Air Quality (KORUS-AQ) field study. ELEMENTA (WASHINGTON, D.C.) 2021; 9:1-27. [PMID: 34926709 PMCID: PMC8675105 DOI: 10.1525/elementa.2020.00163] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The Korea-United States Air Quality (KORUS-AQ) field study was conducted during May-June 2016. The effort was jointly sponsored by the National Institute of Environmental Research of South Korea and the National Aeronautics and Space Administration of the United States. KORUS-AQ offered an unprecedented, multi-perspective view of air quality conditions in South Korea by employing observations from three aircraft, an extensive ground-based network, and three ships along with an array of air quality forecast models. Information gathered during the study is contributing to an improved understanding of the factors controlling air quality in South Korea. The study also provided a valuable test bed for future air quality-observing strategies involving geostationary satellite instruments being launched by both countries to examine air quality throughout the day over Asia and North America. This article presents details on the KORUS-AQ observational assets, study execution, data products, and air quality conditions observed during the study. High-level findings from companion papers in this special issue are also summarized and discussed in relation to the factors controlling fine particle and ozone pollution, current emissions and source apportionment, and expectations for the role of satellite observations in the future. Resulting policy recommendations and advice regarding plans going forward are summarized. These results provide an important update to early feedback previously provided in a Rapid Science Synthesis Report produced for South Korean policy makers in 2017 and form the basis for the Final Science Synthesis Report delivered in 2020.
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Affiliation(s)
| | - Joon-Young Ahn
- Air Quality Research Division, National Institute of Environmental Research, Incheon, Republic of Korea
| | | | - Limseok Chang
- Air Quality Research Division, National Institute of Environmental Research, Incheon, Republic of Korea
| | | | - Jhoon Kim
- Yonsei University, Seoul, Republic of Korea
| | - Gangwoong Lee
- Hankuk University of Foreign Studies, Seoul, Republic of Korea
| | - Jeong-Hoo Park
- Air Quality Research Division, National Institute of Environmental Research, Incheon, Republic of Korea
| | | | | | - Chang-Keun Song
- Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Ji-Hyung Hong
- Air Quality Research Division, National Institute of Environmental Research, Incheon, Republic of Korea
- Inha University, Incheon, Republic of Korea
| | - You-Deog Hong
- Air Quality Research Division, National Institute of Environmental Research, Incheon, Republic of Korea
- Kum Kyoung Engineering, Seoul, Republic of Korea
| | | | - Meehye Lee
- Korea University, Seoul, Republic of Korea
| | - Taehyoung Lee
- Hankuk University of Foreign Studies, Seoul, Republic of Korea
| | | | - Kyung-Eun Min
- Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | | | - Hye Jung Shin
- Air Quality Research Division, National Institute of Environmental Research, Incheon, Republic of Korea
| | - Young-Woo Kim
- Air Quality Research Division, National Institute of Environmental Research, Incheon, Republic of Korea
| | - Jin-Soo Choi
- Air Quality Research Division, National Institute of Environmental Research, Incheon, Republic of Korea
| | - Jin-Soo Park
- Air Quality Research Division, National Institute of Environmental Research, Incheon, Republic of Korea
| | - James J. Szykman
- US Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC, USA
| | - Russell W. Long
- US Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC, USA
| | - Carolyn E. Jordan
- NASA Langley Research Center, Hampton, VA, USA
- National Institute of Aerospace, Hampton, VA, USA
| | | | - Alan Fried
- University of Colorado, Boulder, CO, USA
| | | | | | - Yong Pyo Kim
- Ewha Womans University, Seoul, Republic of Korea
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9
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Gil J, Kim J, Lee M, Lee G, An J, Lee D, Jung J, Cho S, Whitehill A, Szykman J, Lee J. Characteristics of HONO and its impact on O 3 formation in the Seoul Metropolitan Area during the Korea-US Air Quality Study. ATMOSPHERIC ENVIRONMENT (OXFORD, ENGLAND : 1994) 2021; 247:10.1016/j.atmosenv.2020.118182. [PMID: 33746556 PMCID: PMC7970509 DOI: 10.1016/j.atmosenv.2020.118182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Photolysis of nitrous acid (HONO) is recognized as an early-morning source of OH radicals in the urban air. During the Korea-US air quality (KORUS-AQ) campaign, HONO was measured using quantum cascade - tunable infrared laser differential absorption spectrometer (QC-TILDAS) at Olympic Park in Seoul from 17 May, 2016 to 14 June, 2016. The HONO concentration was in the range of 0.07-3.46 ppbv, with an average of 0.93 ppbv. Moreover, it remained high from 00:00-05:00 LST. During this time, the mean concentration was higher during the high-O3 episodes (1.82 ppbv) than the non-episodes (1.20 ppbv). In the morning, the OH radicals that were produced from HONO photolysis were 50% higher (0.95 pptv) during the high-O3 episodes than the non-episodes. Diurnal variations in HOx and O3 concentrations were simulated by the F0AM model, which revealed a difference of ~20 ppbv in the daily maximum O3 concentrations between the high-O3 episodes and non-episodes. Furthermore, the HONO concentration increased with an increase in relative humidity (RH) up to 80%; the highest HONO was associated with the top 10% NO2 in each RH group, confirming that NO2 is one of the main precursors of HONO. At night, the conversion ratio of NO2 to HONO was estimated to be 0.88×10-2 h-1; this ratio was found to increase with an increase in RH. The Aitken mode particles (30-120 nm), which act as catalyst surfaces, exhibited a similar tendency with a conversion ratio that increased along with RH, indicating the coupling of surfaces with HONO conversion. Using an artificial neural network (ANN) model, HONO concentrations were successfully simulated with measured variables (r2 = 0.66 as an average of five models). Among these variables, NOx, aerosol surface area, and RH were found to be the main factors affecting the ambient HONO concentrations. The results reveal that RH facilitates the conversion of NO2 to HONO by constraining the availability of aerosol surfaces. This study demonstrates the coupling of HONO with the HOx-O3 cycle in the Seoul Metropolitan Area (SMA) and provides practical evidence of the heterogeneous formation of HONO by employing the ANN model.
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Affiliation(s)
- Junsu Gil
- Department of Earth and Environmental Science, Korea University, Seoul, South Korea
| | - Jeonghwan Kim
- Department of Environmental Science, Hankuk University of Foreign Studies, Yongin, South Korea
| | - Meehye Lee
- Department of Earth and Environmental Science, Korea University, Seoul, South Korea
| | - Gangwoong Lee
- Department of Environmental Science, Hankuk University of Foreign Studies, Yongin, South Korea
| | - Joonyeong An
- National Institute of Environmental Research (NIER), Incheon, South Korea
| | - Dongsoo Lee
- Department of Chemistry, Yonsei University, Seoul, South Korea
| | - Jinsang Jung
- Korea Research Institute of Standards and Science (KRISS), Daejeon, South Korea
| | - Seogju Cho
- Seoul Research Institute of Public Health and Environment, Seoul, South Korea
| | - Andrew Whitehill
- U.S. Environmental Protection Agency, Research Triangle Park, Durham, USA
| | - James Szykman
- U.S. Environmental Protection Agency, Research Triangle Park, Durham, USA
| | - Jeonghoon Lee
- School of Mechanical Engineering, Korea University of Technology and Education, Cheonan, South Korea
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Kim H, Gil J, Lee M, Jung J, Whitehill A, Szykman J, Lee G, Kim DS, Cho S, Ahn JY, Hong J, Park MS. Factors controlling surface ozone in the Seoul Metropolitan Area during the KORUS-AQ campaign. ELEMENTA (WASHINGTON, D.C.) 2020; 8:10.1525/elementa.444. [PMID: 34522698 PMCID: PMC8437047 DOI: 10.1525/elementa.444] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
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 O3, NOx, NOy, SO2, CO, and volatile organic compounds (VOCs), photochemical byproducts such as H2O2 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 O3 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 NOx and VOC as well as O3. During such episodes, the nighttime NOx 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 O3 episodes. This study revealed that toluene was the most abundant VOC in Seoul, and its concentration increased greatly with NOx due to the large local influence under stagnant conditions. When O3 was highly elevated concurrently with PM2.5 under dominant westerlies, NOx and VOCs were relatively lower and CO was noticeably higher than in other episodes. Additionally, the O3 production efficiency was the highest due to a low NOx with the highest NOz/NOy 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 NOx titration. Overall, the Seoul Metropolitan Area is at NOx-saturated and VOC-limited conditions, which was diagnosed by indicator species and VOC/NOx ratios.
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Affiliation(s)
- Heejeong Kim
- Department of Earth and Environmental Sciences, Korea University, Seoul, KR
| | - Junsu Gil
- Department of Earth and Environmental Sciences, Korea University, Seoul, KR
| | - Meehye Lee
- Department of Earth and Environmental Sciences, Korea University, Seoul, KR
| | - Jinsang Jung
- Center for Gas Analysis, Korea Research Institute of Standards and Science, Daejeon, KR
| | | | | | - Gangwoong Lee
- Department of Environmental Sciences, Hankuk University of Foreign Studies, Yongin, KR
| | - Deug-Soo Kim
- Department of Environmental Engineering, Kunsan National University, Kunsan, KR
| | - Seogju Cho
- Seoul Metropolitan Government Research Institute of Public Health and Environment, Gyeonggi-do, KR
| | - Jun-Young Ahn
- Department of Climate and Air Quality, National Institute of Environmental Research, Incheon, KR
| | - Jinkyu Hong
- Department of Atmospheric Sciences, Yonsei University, Seoul, KR
| | - Moon-Soo Park
- Research Center for Atmospheric Environment, Hankuk University of Foreign Sturdies, Yongin, KR
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