EGU21-4995
https://doi.org/10.5194/egusphere-egu21-4995
EGU General Assembly 2021
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

New Fractional Release Factors, Ozone Depletion Potentials, and Lifetimes for Four Long-Lived CFCs: CFC-13, CFC-114, CFC-114a, and CFC-115

Elinor Tuffnell1,2, Johannes Laube2, Emma Leedham Elvidge4, Bill Sturges5, Karina Adcock1,5, Paul Fraser3, Paul Krummel3, Ray Langenfelds3, Dave Oram1,5,6, Eric Fleming7,8, Qing Liang7, and Thomas Roeckmann9
Elinor Tuffnell et al.
  • 1The University of East Anglia, Environmental Science, Norwich, United Kingdom of Great Britain – England, Scotland, Wales (e.tuffnell@uea.ac.uk)
  • 2Institute of Energy and Climate Research: Stratosphere, Jülich Research Centre, Jülich, 52428, Germany.
  • 3Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Victoria, Australia.
  • 4Faculty of Science, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
  • 5Centre for Ocean and Atmospheric Sciences, School of Environmental Sciences, University of East Anglia, Norwich, UK.
  • 6National Centre for Atmospheric Science, School of Environmental Sciences, University of East Anglia, Norwich, UK.
  • 7NASA Goddard Space Flight Center, Greenbelt, MD, USA
  • 8Science Systems and Applications, Inc., Lanham, MD, USA.
  • 9Institute for Marine and Atmospheric research Utrecht (IMAU), Utrecht University (UU), Utrecht, the Netherlands.

Knowing the stratospheric lifetime of an Ozone Depleting Substance (ODS), and its potential depletion of ozone during that time, is vital to reliably monitor and control the use of ODSs. Here, we present improved policy-relevant parameters: Fractional Release Factors (FRFs), Ozone Depletion Potentials (ODPs), and stratospheric lifetimes, for four understudied long-lived CFCs: CFC-13 (CClF3), CFC-114 (CClF2CCCLF2), CFC-114a (CCl2FCF3), and CFC-115 (C2ClF5). Previously derived lifetime estimates for CFC-114 and CFC-115 have substantial uncertainties, while lifetime uncertainties for CFC-13 and CFC-114a are absent from the peer-reviewed literature (Carpenter & Danie et al, 2018).

This study used both observational and model data to investigate these compounds and this work derives, for the first time, observation-based lifetimes utilising measurements of air samples collected in the stratosphere. We also used a version of the NASA Goddard Space Flight Center (GSFC) 2-D atmospheric model driven by temperature and transport fields derived from MERRA/MERRA-2 reanalysis.

FRFs for these compounds, which had been lacking until now, were derived using stratospheric air samples collected from several research flights with the high-altitude aircraft M55-Geophysica, and the background trend from archived surface air samples from Cape Grim, Tasmania.

 By using a previously-published correlation between lifetime and FRF for seven well-characterised compounds (CF4, C2F6, C3F8, CHF3, HFC-125, HFC-227ea and SF6), we were able to derive lifetimes for these four new species. Lifetime estimates for CFC-114a agreed within the uncertainties (agreement to one sigma) with the lifetime estimates compiled in Burkholder et al. (2018), while the one for CFC-114 agreed within 2 sigma (measurement-related uncertainties) with those cited in Burkholder et al. (2018). However, observation-based lifetimes for CFC-13 and CFC-115 only agreed with those in Burkholder et al. (2018) within 3 sigma. The lifetime uncertainties in this study were reduced compared to those in Carpenter & Danie et al (2018).

As our lifetime estimates for these latter two compounds are notably lower than previous estimates, this suggests that these two compounds may have had greater emissions than previously thought, in order to account for their abundance. It also implies that they will be removed from the atmosphere more quickly than previously thought.

New ODPs were derived for these compounds from their new lifetimes and FRFs. Since for two of these compounds (CFC-13 and CFC-114a), there is an absence of observation-derived ODPs in the peer-reviewed literature, this is new and relevant information. The ODPs for CFC-114 and CFC-115 are comparable with estimates from the most recent Scientific Assessment of Ozone Depletion (Burkholder et al., 2018). Providing new and updated lifetimes, FRFs and ODPs for these compounds will help improve future estimates of their tropospheric emissions and their resulting damage to the stratospheric ozone layer.

             

References

Burkholder et al. (2018). Appendix A, Table A-1 in Scientific Assessment of Ozone Depletion: 2018, Global Ozone Research and Monitoring Project, Report No. 58, World Meteorological Organization, Geneva, Switzerland,  http://ozone.unep.org/science/assessment/sap.

Carpenter, L.J., Danie, J.S. et al (2018). Scenarios and Information for Policymakers Chapter 6, Table 6-1 in Scientific Assessment of Ozone Depletion: 2018, Global Ozone Research and Monitoring Project, Report No. 58, World Meteorological Organization, Geneva, Switzerland.

How to cite: Tuffnell, E., Laube, J., Leedham Elvidge, E., Sturges, B., Adcock, K., Fraser, P., Krummel, P., Langenfelds, R., Oram, D., Fleming, E., Liang, Q., and Roeckmann, T.: New Fractional Release Factors, Ozone Depletion Potentials, and Lifetimes for Four Long-Lived CFCs: CFC-13, CFC-114, CFC-114a, and CFC-115, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4995, https://doi.org/10.5194/egusphere-egu21-4995, 2021.

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