Cloud Forming Potential of Marine Biogenic Aerosols and Their Physiochemical Properties

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This project will investigate the hypothesis that many types of marine primary organic aerosols (POA) including phytoplankton, act as efficient ice nuclei (IN) under atmospherically relevant conditions. The experiments will build upon previous studies by experimentally examining the physical and chemical characteristics of other marine organic and biogenic constituents present in the sub-micrometer sized particles, which can be most easily carried aloft, that allow these particles to act as efficient IN and under what conditions. Not only will the governing mechanisms relevant for the aerosol life cycle at temperatures below the freezing point be identified for a variety of POA, but the ability to derive ice nucleation parameterizations, will enable climate modelers to include the formation of ice crystals and clouds in climate models for better understanding the hydrological cycle and radiative forcing. Perhaps most significantly, the novel experimental approach for studying ice nucleation in combination with micro-spectroscopic single particle analytical tools using specific staining and epifluroescence microscopy, scanning electron microscopy (SEM), near-edge x-ray absorption fine structure (STXM/NEXAFS) spectroscopy, and computer controlled scanning electron microscopy and energy dispersive analysis of x-rays (CCSEM/EDX and HRTEM/EELS), will allow the specific physiochemical properties of particles which do and do not nucleate ice to be contrasted.The results of this project have the potential to shift paradigms regarding the fine scale picture of heterogeneous ice nucleation and thus can change the way aerosol induce ice nucleation, and thus ice cloud formation processes, are represented in models. The long-term economic benefits to federal, state, and local governments of better understanding hydrological cycles and being able to predict rates and the nature of climate changes are great. Collaborations with scientists at Lawrence Berkeley and Battelle Pacific Northwest National Laboratories will allow synergistic expansion of the scope and depth of the research and will significantly enhance the experience of students. They will also provide an opportunity for the investigators to obtain knowledge that will be transmitted to other scientists through publications in peer-reviewed journals and presentations at national/international multi- and interdisciplinary conferences. The project will allow the research group to extend its history of being involved with public outreach projects and mentoring male and female graduate, undergraduate, and high school students of diverse ethnic backgrounds and nationalities. Promoting the development of the next generation of scientists engaged in cutting edge research, having access to sophisticated state-of-the-art analytical equipment, trained in experimental procedures, quantitative data analysis, and numerical modeling techniques is critical for understanding the link between the Earth's oceans and atmosphere and addressing global climate change issues.