Atmospheric lifetimes, infrared absorption spectra, radiative forcings and global warming potentials of NF<sub>3</sub> and CF<sub>3</sub>CF<sub>2</sub>Cl (CFC-115)

Abstract

Abstract. Fluorinated compounds such as NF 3 and C 2 F 5 Cl (CFC-115) are characterised by very large global warming potentials (GWPs), which result from extremely long atmospheric lifetimes and strong infrared absorptions in the atmospheric window. In this study we have experimentally determined the infrared absorption cross sections of NF 3 and CFC-115, calculated the radiative forcing and efficiency using two radiative transfer models and identified the effect of clouds and stratospheric adjustment. The infrared cross sections are within 10 % of previous measurements for CFC-115 but are found to be somewhat larger than previous estimates for NF3, leading to a radiative efficiency for NF 3 that is 25 % larger than that quoted in the Intergovernmental Panel on Climate Change Fifth Assessment Report. A whole atmosphere chemistry-climate model was used to determine the atmospheric lifetimes of NF 3 and CFC-115 to be (509 ± 21) years and (492 ± 22) years, respectively.

Determination of the atmospheric lifetime and global warming potential of sulfur hexafluoride using a three-dimensional model

“…Employing profiles averaged over the lowerresolution grid gives an average forcing within 1 % of the higher-resolution grid. Using only a single annually averaged global mean profile led to a 10 % error in radiative forcing when compared to our monthly resolved high-resolution profile, supporting the findings of Freckleton et al (1998) and Totterdill et al (2016).…”

“…The radiative efficiency was calculated in the RFM for each month between 90 • S and 90 • N at latitudinal resolutions (on which the data were averaged to obtain the zonal mean vertical profile) of 1.5 and 9.0 • . The tropopause used the standard WMO lapse rate definition (see Totterdill et al, 2016). Figure 10 shows the seasonal-latitudinal variation of the instantaneous clear-sky radiative forcing for SF 6 on the high-(1.5 • ) and low-(9 • ) resolution grids.…”

“…Results obtained from this model were validated against the DISORT radiative transfer solver (Stamnes et al, 2000) included within the libRadtran (Library for Radiative Transfer) package (Mayer and Kylling, 2005). A full description of these models and parameters used alongside discussion of the treatment of clouds and model comparison is also given in Totterdill et al (2016). (Haenel et al, 2015).…”

“…Room temperature (296 ± 2 K) measurements were carried out between 400 and 2000 cm −1 at a spectral resolution of 0.1 cm −1 and compiled from the averaged total of 128 scans to 32 background scans at a scanner velocity of 1.6 kHz. Gas mixtures were made using between 8 and 675 Torr of SF 6 diluted up to an atmosphere using N 2 , according to the method described in Totterdill et al (2016).…”

Atmospheric histories and emissions of chlorofluorocarbons CFC-13(CClF<sub>3</sub>), CFC-114 (C<sub>2</sub>Cl<sub>2</sub>F<sub>4</sub>), and CFC-115 (C<sub>2</sub>ClF<sub>5</sub>)

“…The firn model used here was developed at CSIRO by Trudinger et al (1997) and updated by Trudinger et al (2013). It has previously been used for firn air measurement reconstructions of other greenhouse gases Trudinger et al, 2002Trudinger et al, , 2016Vollmer et al, 2016).…”