Resolution of the uncertainties in the radiative forcing of HFC-134a

Piers M.De F. Forster, J. B. Burkholder, C. Clerbaux, P. F. Coheur, M. Dutta, L. K. Gohar, M. D. Hurley, G. Myhre, R. W. Portmann, K. P. Shine, T. J. Wallington, D. Wuebbles

Research output: Contribution to journalArticlepeer-review

Abstract

HFC-134a (CF3CH2F) is the most rapidly growing hydrofluorocarbon in terms of atmospheric abundance. It is currently used in a large number of household refrigerators and air-conditioning systems and its concentration in the atmosphere is forecast to increase substantially over the next 50-100 years. Previous estimates of its radiative forcing per unit concentration have differed significantly ∼25%. This paper uses a two-step approach to resolve this discrepancy. In the first step six independent absorption cross section datasets are analysed. We find that, for the integrated cross section in the spectral bands that contribute most to the radiative forcing, the differences between the various datasets are typically smaller than 5% and that the dependence on pressure and temperature is not significant. A "recommended" HFC-134a infrared absorption spectrum was obtained based on the average band intensities of the strongest bands. In the second step, the "recommended" HFC-134a spectrum was used in six different radiative transfer models to calculate the HFC-134a radiative forcing efficiency. The clear-sky instantaneous radiative forcing, using a single global and annual mean profile, differed by 8%, between the 6 models, and the latitudinally-resolved adjusted cloudy sky radiative forcing estimates differed by a similar amount. We calculate that the radiative forcing efficiency of HFC-134a is 0.16 ± 0.02 Wm-2 ppbv-1.

Original languageEnglish (US)
Pages (from-to)447-460
Number of pages14
JournalJournal of Quantitative Spectroscopy and Radiative Transfer
Volume93
Issue number4
DOIs
StatePublished - Jul 15 2005

Keywords

  • Global warming potential
  • HFC-134a
  • Radiative forcing
  • Uncertainties

ASJC Scopus subject areas

  • Radiation
  • Atomic and Molecular Physics, and Optics
  • Spectroscopy

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