CAREER: Organic Aerosol Volatility, Phase and Partitioning

大气气溶胶粒子通过吸收和散射太阳辐射并影响云的性质，在地球气候系统中发挥着重要作用。气溶胶颗粒对气候的具体影响在很大程度上取决于它们的组成，但关于它们的形成、化学演变和消除仍有许多未知之处，特别是在考虑有机气溶胶的情况下。因此，大气气溶胶造成的气候强迫仍然高度不确定，从而阻碍了目前对未来气候变化的理解和预测。这一职业奖支持详细的实验和分析，这些实验和分析将解决与大气气溶胶中有机化合物的气体-颗粒分配有关的基本问题，特别关注在颗粒组成、物相和挥发性之间建立联系。目前，环境和模拟的有机气溶胶挥发性之间存在着显著的差异，这表明模拟的气溶胶的物理性质是不正确的。吸收分配理论构成了包括有机气溶胶形成在内的大多数区域和全球模型的基础，从而确定了对空气质量和气候的最终影响。最近的实验表明，吸收分配理论可能不像通常假设的那样广泛适用，可能是因为有机气溶胶以玻璃态存在，而不是液态。如果这一发现是正确的，这一发现不仅对理解有机气溶胶的形成，而且对了解大气中有机气溶胶的生命周期都有意义。这些研究将通过实验室实验和对野外数据的分析，解决我们对分配理论在什么条件下能(或不能)描述有机气溶胶的物理行为的理解，这在多大程度上是由颗粒相决定的，以及这是如何影响颗粒挥发的。教育活动将包括：(1)为教科书《物理地质学》编写关于全球气候变化的新章节，这本书在全国数百个地球科学入门课堂中使用；(2)开发和教授一个以墨西哥城空气污染问题为重点的单元，将其纳入一个入门级别的“以地点为基础的”地球科学课程，目的是让在地球科学领域任职人数极少的拉美裔学生参与进来。该模块将为学生提供一个新的动手元素，为他们中的一些人提供在首席研究员实验室进行研究的机会，并加强加州大学戴维斯分校与附近的加州州立大学萨克拉门托分校之间的联系，这是一所主要面向本科生的机构。研究生将参与该单元开发和教学的所有阶段，为他们提供作为教育工作者发展的机会；以及(3)组织一个多机构、基于网络的联合小组会议，有专注于大气化学研究的早期教师参加。这个项目的主要目的是为研究生提供更频繁地与他们的同龄人接触的机会，作为科学家发展更多的社区意识，并在“进行中”的研究阶段从广泛的人那里获得反馈。

Atmospheric aerosol particles play an important role in the Earth's climate system through their ability to absorb and scatter solar radiation and influence the properties of clouds. To a large extent the specific influence of aerosol particles on climate is determined by their composition, yet much remains unknown with respect to their formation, chemical evolution and removal, especially when considering organic aerosols. As a result, the climate forcing due to atmospheric aerosols remains highly uncertain, thus hampering current understanding and predictions of future climate change. This CAREER award supports detailed experiments and analysis that will address fundamental questions related to gas-particle partitioning of organic compounds in atmospheric aerosols, with a particular focus on making connections between particle composition, phase and volatility. Currently, there exists a significant discrepancy between ambient and modeled organic aerosol volatility, indicating that the physical properties of the modeled aerosol are incorrect. Absorptive partitioning theory forms the basis of most regional and global models that include organic aerosol formation, thereby determining the eventual impacts on air quality and climate. Recent experiments suggest that absorptive partitioning theory may not be as broadly applicable as is typically assumed, perhaps because the organic aerosol exists with a glassy, as opposed to liquid-like, phase. If correct, this finding has implications for understanding not only organic aerosol formation, but also the lifecycle of organic aerosol in the atmosphere. The studies will address, through laboratory experiments and analysis of field data, our understanding of under what conditions partitioning theory does (or does not) work to describe the physical behavior of organic aerosols, to what extent this is determined by particle phase, and how this influences particle volatility.Educational activities will include: (1) Authoring a new chapter on global climate change for the textbook Physical Geology, which is used in hundreds of introductory geoscience classrooms across the country; (2) Developing and teaching a module focused on air pollution issues in Mexico City for incorporation in an introductory-level "place-based" geoscience course with the objective of engaging Hispanic students, who are extremely under-represented in the geosciences. The module will provide a new, hands-on element for the students, provide some of them with research opportunities in the principal investigator's laboratory and serve to strengthen ties between UC Davis and nearby California State University, Sacramento, which is a predominately undergraduate-serving institution. Graduate students will be involved at all stages of the development and teaching of the module, providing them a chance to develop as educators; and (3) Organizing a multi-institution, web-based joint group meeting that involves early-career faculty members whose research focuses on atmospheric chemistry. The primary intention of this project is to provide graduate students opportunities to more frequently engage with their peers, develop a greater sense of community as scientists and to obtain feedback from a broad spectrum of people at the "in progress" stage of research.