Jordan, Carolyn E. Crawford, James H. Beyersdorf, Andreas J. Eck, Thomas F. Halliday, Hannah S. Nault, Benjamin A. Chang, Lim-Seok Park, JinSoo Park, Rokjin Lee, Gangwoong Kim, Hwajin Ahn, Jun-Young Cho, Seogju Shin, Hye Jung Lee, Jae Hong Jung, Jinsang Kim, Deug-Soo Lee, Meehye Lee, Taehyoung Whitehill, Andrew Szykman, James Schueneman, Melinda K. Campuzano-Jost, Pedro Jimenez, Jose L. DiGangi, Joshua P. Diskin, Glenn S. Anderson, Bruce E. Moore, Richard H. Ziemba, Luke D. Fenn, Marta A. Hair, Johnathan W. Kuehn, Ralph E. Holz, Robert E. Chen, Gao Travis, Katherine Shook, Michael Peterson, David A. Lamb, Kara D. Schwarz, Joshua P. 2024-01-19T17:03:38Z 2024-01-19T17:03:38Z 2021-09-05 2020-07-01 2325-1026 https://pubs.kist.re.kr/handle/201004/118408 The Korea - United States Air Quality Study (May - June 2016) deployed instrumented aircraft and ground-based measurements to elucidate causes of poor air quality related to high ozone and aerosol concentrations in South Korea. This work synthesizes data pertaining to aerosols (specifically, particulate matter with aerodynamic diameters <2.5 micrometers, PM2.5) and conditions leading to violations of South Korean air quality standards (24-hr mean PM2.5 < 35 mu g m(-3)). PM2.5 variability from AirKorea monitors across South Korea is evaluated. Detailed data from the Seoul vicinity are used to interpret factors that contribute to elevated PM2.5. The interplay between meteorology and surface aerosols, contrasting synoptic-scale behavior vs. local influences, is presented. Transboundary transport from upwind sources, vertical mixing and containment of aerosols, and local production of secondary aerosols are discussed. Two meteorological periods are probed for drivers of elevated PM2.5. Clear, dry conditions, with limited transport (Stagnant period), promoted photochemical production of secondary organic aerosol from locally emitted precursors. Cloudy humid conditions fostered rapid heterogeneous secondary inorganic aerosol production from local and transported emissions (Transport/Haze period), likely driven by a positive feedback mechanism where water uptake by aerosols increased gas-to-particle partitioning that increased water uptake. Further, clouds reduced solar insolation, suppressing mixing, exacerbating PM2.5 accumulation in a shallow boundary layer. The combination of factors contributing to enhanced PM2.5 is challenging to model, complicating quantification of contributions to PM2.5 from local versus upwind precursors and production. We recommend co-locating additional continuous measurements at a few AirKorea sites across South Korea to help resolve this and other outstanding questions: carbon monoxide/carbon dioxide (transboundary transport tracer), boundary layer height (surface PM2.5 mixing depth), and aerosol composition with aerosol liquid water (meteorologically-dependent secondary production). These data would aid future research to refine emissions targets to further improve South Korean PM2.5 air quality. English UNIV CALIFORNIA PRESS LIQUID WATER DRIVEN SEVERE WINTER HAZE ORGANIC AEROSOL NITRATE FORMATION HETEROGENEOUS HYDROLYSIS PARTICULATE NITRATE THERMODYNAMIC MODEL HIGH-RESOLUTION REACTIVE UPTAKE NORTHERN CHINA Investigation of factors controlling PM2.5 variability across the South Korean Peninsula during KORUS-AQ Article 10.1525/elementa.424 1 ELEMENTA-SCIENCE OF THE ANTHROPOCENE, v.8 ELEMENTA-SCIENCE OF THE ANTHROPOCENE 8 scie scopus 000545313100001 Environmental Sciences Meteorology & Atmospheric Sciences Environmental Sciences & Ecology Meteorology & Atmospheric Sciences Article LIQUID WATER DRIVEN SEVERE WINTER HAZE ORGANIC AEROSOL NITRATE FORMATION HETEROGENEOUS HYDROLYSIS PARTICULATE NITRATE THERMODYNAMIC MODEL HIGH-RESOLUTION REACTIVE UPTAKE NORTHERN CHINA PM2.5 Aerosols Air quality South Korea KORUS-AQ