Collaborative Research: Organic Trace Gas Studies from Whole-Air Sampling of the Impact of Megacities and Intercontinental Transport on Regional and Global Environments

该项目支持使用空中和地面全空气采样（WAS）测量碳氢化合物、卤代烃、硫化合物、有机硝酸盐和选定的含氧挥发性有机化合物（VOC），并随后使用气相色谱/质谱/火焰离子化检测/电子捕获检测进行分析。测量将在NCAR C-130飞机上进行，并从墨西哥城附近的一个地面站点进行。这些测量结果将有助于MIRAGE-Mex（特大城市对区域和全球环境的影响）和IMPEX（洲际和特大城市污染实验）：空中测量将是综合仪器有效载荷的一部分，以检查墨西哥城污染羽流进入区域大气的程度和持久性，研究墨西哥城排放物在氧化剂形成和气体-颗粒过程方面的反应化学，了解活性氮的转化和分配，并评估化学和气溶胶排放和转化对区域辐射收支的影响和反馈。监测不同反应性的有机气体的变化，包括第二代氧化产物的形成和损失，对于测试对城市羽流化学反应性的理解和测试二次有机气溶胶形成和增长的模型是必要的。墨西哥城地区的地面测量将是一套拟议测量的一部分，这套拟议测量将有助于确定最初的化学边界条件和都市地区排放的早期光化学处理，IMPEX部署部分将侧重于研究污染物从亚洲向北美大陆的洲际运输的影响。为此，C-130将驻扎在华盛顿州的西雅图或附近，并与美国宇航局的DC-8飞机协调进行研究飞行。该项目将为几名研究生提供教育机会。该项目将促进技术专长和教育机会的国际交流，这将有助于在国际上培养未来的科学家。

This project supports measurements of hydrocarbons, halocarbons, sulfur compounds, organic nitrates, and selected oxygenated volatile organic compounds (VOCs) using airborne and ground-based whole air sampling (WAS) and subsequent analysis with gas chromatography/mass spectrometry/flame ionization detection/electron capture detection. Measurements will be carried out onboard the NCAR C-130 aircraft, and from one ground-site near Mexico City. These measurements will contribute both to MIRAGE-Mex (Megacity Impacts on Regional and Global Environment) and IMPEX (Intercontinental and Megacity Pollution Experiment).The airborne measurements will be part of an integrated instrument payload to examine the extent and persistence of the Mexico City pollution plume into the regional atmosphere, to study the reactive chemistry of Mexico City emissions in terms of oxidant formation and gas-particle processes, to understand the transformation and partitioning of reactive nitrogen, and to evaluate the effects and feedbacks of the chemical and aerosol emissions and transformations on the regional radiative budget. Monitoring changes of organic gases of different reactivity, including the formation and loss of second generation oxidation products) are necessary to test understanding of the chemical reactivity of the urban plume and to test models of secondary organic aerosol formation and growth. The ground-based measurements in the Mexico City area will be part of a suite of proposed measurements that will help define the initial chemical boundary conditions and early photochemical processing of emissions from the metropolitan area.The IMPEX portion of the deployment will focus on studying the impact of intercontinental transport of pollutants from Asia to the North American continent. For that purpose, the C-130 will be stationed in or near Seattle, WA, and carry out research flights coordinated with the NASA DC-8 aircraft.This project will provide educational opportunities for several graduate students. The project will foster international exchange of technical expertise and educational opportunities that will help train future scientists internationally.