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
National Institute of Aerospace, Hampton, Virginia, US.
NASA Langley Research Center, Hampton, Virginia, US.
Elementa (Wash D C). 2020;8(28). doi: 10.1525/elementa.424.
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, PM) and conditions leading to violations of South Korean air quality standards (24-hr mean PM < 35 μg m). PM variability from AirKorea monitors across South Korea is evaluated. Detailed data from the Seoul vicinity are used to interpret factors that contribute to elevated PM. 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 PM. 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 PM accumulation in a shallow boundary layer. The combination of factors contributing to enhanced PM is challenging to model, complicating quantification of contributions to PM 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 PM 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 PM air quality.
韩美空气质量研究（2016年5月至6月）部署了仪器装备的飞机和地面测量设备，以阐明韩国空气质量差与高臭氧和气溶胶浓度相关的原因。这项工作综合了与气溶胶（具体而言，空气动力学直径<2.5微米的颗粒物，即PM）以及导致违反韩国空气质量标准（24小时平均PM<35微克/立方米）的条件相关的数据。评估了韩国各地“韩国空气”监测站的PM变异性。利用首尔附近的详细数据来解释导致PM升高的因素。介绍了气象学与地表气溶胶之间的相互作用，对比了天气尺度行为与局部影响。讨论了来自上游源的越境传输、气溶胶的垂直混合与截留以及二次气溶胶的局地生成。探究了两个气象时期导致PM升高的驱动因素。晴朗、干燥且传输受限的条件（停滞期）促进了由本地排放前体光化学生成二次有机气溶胶。多云潮湿的条件促进了由本地和传输排放快速非均相生成二次无机气溶胶（传输/霾期），这可能是由一种正反馈机制驱动的，即气溶胶对水的吸收增加了气粒分配，进而增加了水的吸收。此外，云层减少了太阳辐射，抑制了混合，加剧了浅边界层中PM的积累。导致PM增强的多种因素组合难以建模，使得量化本地与上游前体及生成对PM的贡献变得复杂。我们建议在韩国各地的一些“韩国空气”站点进行额外的同步连续测量，以帮助解决这一问题及其他未解决的问题：一氧化碳/二氧化碳（越境传输示踪剂）、边界层高度（地表PM混合深度）以及气溶胶组成与气溶胶液态水（气象依赖的二次生成）。这些数据将有助于未来的研究完善排放目标，以进一步改善韩国的PM空气质量。
