1Earth System Research Laboratory, Chemical Sciences Division,
National Oceanic and Atmospheric Administration, Boulder, Colorado, USA
2Cooperative Institute for Research in Environmental Sciences,
University of Colorado, Boulder, Colorado, USA
3Michigan State University, Lyman Briggs College, East Lansing, Michigan, USA
4NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
5Science Systems and Applications, Inc., Lanham, Maryland, USA
Received: 29 Feb 2016 – Discussion started: 07 Mar 2016
Abstract. The potential impact of CCl2FCF3 (CFC-114a) and the recently observed CCl2FCCl2F (CFC-112), CCl3CClF2 (CFC-112a), and CCl3CF3 (CFC-113a) chlorofluorocarbons (CFCs) on stratospheric ozone and climate is presently not well characterized. In this study, the UV absorption spectra of these CFCs were measured between 192.5 and 235 nm over the temperature range 207–323 K. Precise parameterizations of the UV absorption spectra are presented. A 2-D atmospheric model was used to evaluate the CFC atmospheric loss processes, lifetimes, ozone depletion potentials (ODPs), and the associated uncertainty ranges in these metrics due to the kinetic and photochemical uncertainty. The CFCs are primarily removed in the stratosphere by short-wavelength UV photolysis with calculated global annually averaged steady-state lifetimes (years) of 63.6 (61.9–64.7), 51.5 (50.0–52.6), 55.4 (54.3–56.3), and 105.3 (102.9–107.4) for CFC-112, CFC-112a, CFC-113a, and CFC-114a, respectively. The range of lifetimes given in parentheses is due to the 2σ uncertainty in the UV absorption spectra and O(1D) rate coefficients included in the model calculations. The 2-D model was also used to calculate the CFC ozone depletion potentials (ODPs) with values of 0.98, 0.86, 0.73, and 0.72 obtained for CFC-112, CFC-112a, CFC-113a, and CFC-114a, respectively. Using the infrared absorption spectra and lifetimes determined in this work, the CFC global warming potentials (GWPs) were estimated to be 4260 (CFC-112), 3330 (CFC-112a), 3650 (CFC-113a), and 6510 (CFC-114a) for the 100-year time horizon.
Revised: 31 May 2016 – Accepted: 11 Jun 2016 – Published: 01 Jul 2016
Davis, M. E., Bernard, F., McGillen, M. R., Fleming, E. L., and Burkholder, J. B.: UV and infrared absorption spectra, atmospheric lifetimes, and ozone
depletion and global warming potentials for CCl2FCCl2F (CFC-112),
CCl3CClF2 (CFC-112a), CCl3CF3 (CFC-113a), and
CCl2FCF3 (CFC-114a), Atmos. Chem. Phys., 16, 8043-8052, doi:10.5194/acp-16-8043-2016, 2016.