Evolution of Aerosol Hygroscopicity, Mixing State, and Cloud Activation Efficiency

该项目将在墨西哥城内部和下风的地面站点以及NSF/NCAR C-130飞机上部署和运行一套气溶胶仪器，作为墨西哥城对区域和全球环境的大城市影响（MIRAGE）实验和洲际和大城市污染实验（IMPEX）的一部分。主要目标是在墨西哥城地区内外的地面站点以及飞机上操作高流量串联差分流动性分析仪，以获得尺寸分辨的吸湿性和挥发性的测量结果。亚微米和超微米气溶胶的大小分布将在地表站点使用差分迁移率分析仪和空气动力学粒度仪进行测量。在墨西哥城东北部的主要地面站点运行的串联差分迁移率分析仪将被增强，以允许测量尺寸分辨气溶胶水化状态。云凝结核的浓度和性质将在主站点使用云凝结核计数器和最近研制的云凝结核分离器进行测量。收集到的数据将被综合起来，以提供气溶胶在数小时或数天内演变过程中的大小、吸湿性、挥发性和云成核效率的全面描述。这些测量的结果有望使人们更好地了解主要城市地区的排放对顺风环境的影响。墨西哥和其他国家将受益于这种知识，这可能有助于指导有关环境管理的决定。该项目还将促进美国和墨西哥研究人员之间的伙伴关系。两名研究生将通过这个项目获得实地经验。至少有一名来自墨西哥城的学生将参与数据收集和分析。

This project will deploy and operate a suite of aerosol instruments at surface sites inside and downwind of Mexico City, and on board the NSF/NCAR C-130 aircraft, as part of the Megacity Impacts on Regional and Global Environments (MIRAGE) - Mexico City experiment and the Intercontinental and Megacity Pollution Experiment (IMPEX). The primary objective is to operate high-flow tandem differential mobility analyzers both at surface sites within and outside of Mexico City area as well as on board the aircraft to obtain measurements of size-resolved hygroscopicity and volatility. Submicron and supermicron aerosol size distributions will be measured at the surface sites using differential mobility analyzers and aerodynamic particle sizers. The tandem differential mobility analyzers operated at the main surface site northeast of Mexico City will be augmented to permit measurement of size-resolved aerosol hydration state. The concentration and properties of cloud condensation nuclei will be measured at the main site using a cloud condensation nuclei counter together with a recently developed cloud condensation nuclei separator. The collected data will be integrated to provide a comprehensive description of the size, hygroscopicity, volatility, and cloud nucleating efficiency of the aerosol as it evolves over a period of hours or days. The results of these measurements are expected to lead to an improved understanding of the impact of emissions from a major urban area on the downwind environment. Mexico and other countries will benefit from this knowledge, which may help guide decisions regarding environmental management. The project will also foster partnerships between researchers in the United States and Mexico.Two graduate students will gain field experience through this project. At least one student from Mexico City will be engaged to assist in the data collection and analysis.