Chemical Coupling of Halogens and Oxygenated VOC (Volatile Organic Compounds): Observations, Experiments and Modeling

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This project includes field observations, laboratory experiments, and modeling tasks designed to investigate the chemistry associated with halogens, such as bromine and iodine, in the atmosphere. Measurements will be made at two mountain top observatories (Maido in the Southern Hemisphere tropical Indian Ocean and Mauna Loa in the Northern Hemisphere tropical Pacific Ocean) to assess the seasonal variability of halogen concentrations. This research will provide critical new information for assessing the extent to which tropospheric halogens modify the lifetime of tropospheric ozone, a potent greenhouse gas, and serve as a precursor for the formation of hydroxyl radicals, that influence the lifetime of atmospheric methane. Thus the results will be directly relevant for modeling future climate change.Laboratory experiments will be conducted to investigate the reaction mechanism of bromine radicals with unsaturated oxygenated volatile organic compounds (OVOC) that can form from aliphatic acids in marine air and the potential for product yields of glyoxal and aliphatic aldehydes. Modeling efforts will compare field measurements with the results of global models to assess the impacts of the BrOx sink from OVOC for halogen impacts on tropospheric ozone, methane, and atmospheric mercury.