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.
