Speaker: Prof. Frank Keutsch (University of Wisconsin)
Abstract: Oxidation of volatile organic compounds, especially via the OH radical, is central to formation of tropospheric ozone and secondary organic aerosol, which are climate active and contribute to poor air quality. Recent studies have shown that models underpredict OH radical concentrations by up to a factor of ten in rural areas, implying a profound gap in our understanding. We have developed an approach to constrain ambient OH radical concentrations via measurements of glyoxal enabled by novel instrumentation. Our results suggest that OH radical measurements in one rural area may have been subject to a substantial positive bias and that the discrepancy between modeled and measured OH may be smaller than previously estimated. Glyoxal itself has been implicated as a major global contributor to ambient aerosol mass. We present results that highlight the complexity of glyoxal uptake by aerosols. Our studies reveal pronounced effects of seed-aerosol composition, coatings, and aerosol-phase reactivity on gas/aerosol partitioning, which affects our ability to accurately model the contribution of glyoxal to global aerosol.
Speaker's website: http://www.chem.wisc.edu/users/keutsch