Using Oxygen Isotopes to Constrain Ozone Sources and Sinks

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Ozone plays a critical role in global and regional atmospheric chemistry and has a significant impact on global climate, making it vital to understand ozone source and sink processes. Although substantial progress has been made, there are many open questions regarding ozone dynamics, long-rage transport, and the importance of stratospheric exchange. Variation in the oxygen isotope composition of ozone provides a window into these processes, however, data are very limited because existing methods for sampling ozone for isotopic analysis are complex, cumbersome, and impractical for routine application. Uncertainties in laboratory-determined pressure and temperature dependencies of ozone isotopic composition of ozone also hinder progress. The thrusts of this project are the development and application of a new methodology for determining the oxygen isotopic composition of ozone molecules, and laboratory experiments to determine the pressure and temperatures dependencies of ozone isotope effects under simulated tropospheric conditions. Analysis of daily/nightly ozone isotope composition measurements on the Purdue University campus and in a network of stations across the U.S. for a one-year period will provide new data on the observed pressure and temperature dependence of ozone isotope composition in the troposphere. These data will also give insight into the kinetic isotope effects of ozone oxidation reactions in the atmosphere. The laboratory studies will reduce uncertainties in the theoretical pressure and temperature dependence of ozone isotopic composition, which will then be compared with the field data. In addition to developing an in situ ozone proxy, the data from the laboratory experiments provide insights into the internal distribution of oxygen isotopes in ozone, which will further our understanding of mass independent isotope effects. In addition to improving the understanding of atmospheric ozone cycling, the project will support an early-career investigator, an under-represented group doctoral student, and will continue development of relationships between university researchers and state government agencies. Undergraduate students will also be part of the research team. A volunteer ozone sampling component will incorporate community participation into the project.