HOx Radical Chemistry in Forest Environments: Measurements and Characterization of Instrument Interferences

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This research focuses on the measurement of several of the most important chemical compounds in the atmosphere, the hydroxyl (OH) and hydroperoxy (HO2) radicals. These compounds are important in atmospheric chemistry because they control the lifetimes of many trace gases important to issue of climate change and they can greatly influence air quality. Scientists have found many disagreements between the measurements of these compounds by a variety of methods and by the models that predict their concentrations. This work will investigate the nature of these disagreements and focus on improving the measurement of these compounds, thereby improving the ability of models to better predict climate and air quality.Although there has been reasonable agreement between measured and modeled HOx (OH + HO2) concentrations in urban areas, measurements in forested environments characterized by high mixing ratios of biogenic volatile organic compounds have shown major discrepancies with modeling results. This research includes optimization of the LP/LIF-FAGE instrument, laboratory kinetics experiments, informal instrument intercomparison studies, and investigations of instrument performance in a variety of forest environments under changing environmental conditions. The forest measurements will take place at several locations including the Indiana University Research and Teaching Preserve field lab near the Bloomington campus, the PROPHET (Program for Research on Oxidants: PHotochemistry, Emissions and Transport) site in northern Michigan, as well as at the nearby Forest Accelerated Succession Experiment site. This work will support several graduate students and minority student will be especially encouraged to participate in the research.