Travis Katherine R, Nault Benjamin A, Crawford James H, Kim Hwajin, Chen Qi, Zheng Yan, Liu Tengyu, Jimenez Jose L, Campuzano-Jost Pedro, Wennberg Paul O, Crounse John D, Huey L Gregory
NASA Langley Research Center, Hampton, Virginia 23681-2199, United States.
Aerodyne Research, Inc., CACC Billerica, Massachusetts 01821-3976, United States.
ACS EST Air. 2025 Jul 22;2(8):1758-1769. doi: 10.1021/acsestair.5c00136. eCollection 2025 Aug 8.
Missing sulfate production pathways have been implicated as the cause of model underestimates of sulfate during haze events in East Asia. We add multiphase oxidation of SO in aerosol particles by HO, O, NO, HCHO, and O, catalyzed by transition metal ions (TMIs), to the GEOS-Chem model and evaluate the model with (1) year-round ground-based observations in Seoul, South Korea, (2) airborne observations from the KORUS-AQ field campaign, and (3) fall and winter ground-based observations in Beijing, China. Multiphase chemistry contributes 14% to 90% to total sulfate production depending on the location and season and increases model daily average sulfate by 2 to 3 μg m, with maximum daily increases up to 12 μg m. From winter to summer, oxidation pathways shift, with the largest fraction of multiphase sulfate production occurring during spring and summer due to oxidation by HO. Multiphase oxidation of SO by the HO pathway reduces gas-phase HO concentrations by -40% in spring, which improves model agreement with HO airborne observations. Oxidation pathways also shift between cities, in particular the contribution from the TMI and NO pathways, which are more important in Beijing than in Seoul. This is due to higher levels of transition metals, and a larger impact of an overly shallow mixed layer in Beijing compared to Seoul. The implementation of multiphase aerosol chemistry in GEOS-Chem here allows for the use of this chemistry in other models that can address boundary layer errors, including WRF-GC and CESM-GC. The analysis presented here shows that this chemistry is important to the simulation of sulfate year-round, not only during haze events, and is unique in showing coupled gas- and aerosol-phase impacts of multiphase chemistry.
缺失的硫酸盐生成途径被认为是东亚雾霾事件期间模型低估硫酸盐的原因。我们将由过渡金属离子（TMIs）催化的气溶胶颗粒中SO通过HO、O、NO、HCHO和O进行的多相氧化添加到GEOS-Chem模型中，并使用（1）韩国首尔的全年地面观测数据、（2）KORUS-AQ野外考察的机载观测数据以及（3）中国北京秋冬季节的地面观测数据对模型进行评估。根据地点和季节的不同，多相化学对总硫酸盐生成的贡献为14%至90%，并使模型的日平均硫酸盐增加2至3μg/m³，日最大增加量可达12μg/m³。从冬季到夏季，氧化途径发生变化，由于HO的氧化作用，多相硫酸盐生成的最大比例出现在春季和夏季。HO途径对SO的多相氧化在春季使气相HO浓度降低了40%，这改善了模型与HO机载观测数据的一致性。氧化途径在不同城市之间也有所不同，特别是TMI和NO途径的贡献，在北京比在首尔更为重要。这是由于北京的过渡金属含量较高，且与首尔相比，北京混合层过浅的影响更大。本文在GEOS-Chem中实施多相气溶胶化学，使得该化学过程可应用于其他能够解决边界层误差的模型，包括WRF-GC和CESM-GC。这里给出的分析表明，这种化学过程不仅在雾霾事件期间，而且对全年硫酸盐的模拟都很重要，并且在展示多相化学的气-粒相耦合影响方面具有独特性。
