Park Do-Hyeon, Cho Chaeyoon, Kim Hyeonmin, Park Rokjin J, Anderson Bruce, Lee Taehyoung, Huey Greg L, Wennberg Paul O, Weinheimer Andrew J, Yum Seong Soo, Long Russell, Kim Sang-Woo
School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea.
NASA Langley Research Center, Hampton, VA, USA.
Atmos Res. 2021 Dec 15;264:1-11. doi: 10.1016/j.atmosres.2021.105857.
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) during the entire KORUS-AQ period reached a peak (7,606 ± 12,003 cm ) 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 NO rather than SO-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 NO with OH or O contributed to nitrate formation. From the relationship between N (> 10,000 cm) 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 increased. During the FT SPF case (31 May, 2016) over the yellow sea, the SO-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 SO 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.
在本研究中，我们利用飞机观测数据，对比了在2016年5月至6月美韩空气质量（KORUS-AQ）行动期间，朝鲜半岛边界层（BL）和自由对流层（FT）中负责亚微米颗粒形成（SPF）事件的主要二次无机物种和过程。在整个KORUS-AQ期间，直径在3纳米至10纳米之间的超细颗粒的数量浓度（N）在海拔1公里以下达到峰值（7,606 ± 12,003厘米），这意味着朝鲜半岛周围的颗粒形成主要发生在白天的边界层。在边界层SPF案例（2016年5月7日）中，首尔大都市区的SPF更多归因于NO的氧化而非SO向硫酸盐的转化。通过分析氮氧化率（NOR）与温度或相对湿度（RH）之间的关系，NOR仅与温度呈正相关。这表明NO与OH或O的均相气相反应有助于硝酸盐的形成。从整个KORUS-AQ期间首尔奥林匹克公园的N（> 10,000厘米）与NOR（或硫氧化率）之间的关系来看，随着N的增加，氮氧化的相对重要性似乎在增加。在黄海的自由对流层SPF案例（2016年5月31日）中，SO向硫酸盐的转化似乎对SPF有很大影响。硫酸盐/CO比值与温度和RH均呈正相关，这表明水相途径以及气相反应可能是自由对流层中硫酸盐形成的原因。特别是，5月31日的自由对流层SPF事件可能是在有利于自由对流层SPF事件的条件下，如气溶胶表面积减小和太阳辐射增加，来自大陆的SO前体直接输送到浅海边界层上方所致。
