Improving the Understanding of Halocarbon Lifetimes and Emissions

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This research uses modeling tools to improve the understanding of the emissions and lifetimes in the atmosphere of a broad range of halocarbons, including chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and fully fluorinated compounds such as sulfur hexafluoride (SF-6) and cycloinulohexaose (CF-6). Emissions of halocarbons, including CFCs and HCFCs, contribute to both global climate change and ozone loss, while those of the HFCs and perfluorinated gases contribute to climate change. The results of this research will be relevant to future international assessments of ozone, climate, and chemistry.The three components of this project include: (1) Improved studies of the banks, emissions, lifetimes, and their respective uncertainties for an expanded range of halocarbon gases, using a probabilistic Bayesian model developed and applied previously for CFC-11, -12 and -13; (2) Efforts to examine the potential influence of the ocean and its variability over time on lifetimes, emissions, and regional atmospheric concentrations for a range of halocarbon gases, building on recent modelling work of the significant effects of the ocean on the lifetime of CFC-11; and (3) Research on the interannual dynamical variations in the atmospheric lifetimes, stratospheric-tropospheric exchange, and tropospheric concentrations of halocarbons using a global atmospheric model.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.