Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 10501-10519, 2016
http://www.atmos-chem-phys.net/16/10501/2016/
doi:10.5194/acp-16-10501-2016
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
22 Aug 2016
Satellite observations of stratospheric hydrogen fluoride and comparisons with SLIMCAT calculations
Jeremy J. Harrison1,2, Martyn P. Chipperfield3,4, Christopher D. Boone5, Sandip S. Dhomse3,4, Peter F. Bernath6, Lucien Froidevaux7, John Anderson8, and James Russell III8 1Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
2National Centre for Earth Observation, University of Leicester, Leicester LE1 7RH, UK
3Institute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
4National Centre for Earth Observation, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
5Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
6Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia 23529, USA
7Jet Propulsion Laboratory, Pasadena, California 91109, USA
8Department of Atmospheric and Planetary Sciences, Hampton University, Hampton, Virginia 23668, USA
Abstract. The vast majority of emissions of fluorine-containing molecules are anthropogenic in nature, e.g. chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). Many of these fluorine-containing species deplete stratospheric ozone and are regulated by the Montreal Protocol. Once in the atmosphere they slowly degrade, ultimately leading to the formation of hydrogen fluoride (HF), the dominant reservoir of stratospheric fluorine due to its extreme stability. Monitoring the growth of stratospheric HF is therefore an important marker for the success of the Montreal Protocol.

We report the comparison of global distributions and trends of HF measured in the Earth's atmosphere by the satellite remote-sensing instruments ACE-FTS (Atmospheric Chemistry Experiment Fourier transform spectrometer), which has been recording atmospheric spectra since 2004, and HALOE (HALogen Occultation Experiment), which recorded atmospheric spectra between 1991 and 2005, with the output of SLIMCAT, a state-of-the-art three-dimensional chemical transport model. In general the agreement between observation and model is good, although the ACE-FTS measurements are biased high by  ∼  10 % relative to HALOE. The observed global HF trends reveal a substantial slowing down in the rate of increase of HF since the 1990s: 4.97 ± 0.12 % year−1 (1991–1997; HALOE), 1.12 ± 0.08 % year−1 (1998–2005; HALOE), and 0.52 ± 0.03 % year−1 (2004–2012; ACE-FTS). In comparison, SLIMCAT calculates trends of 4.01, 1.10, and 0.48 % year−1, respectively, for the same periods; the agreement is very good for all but the earlier of the two HALOE periods. Furthermore, the observations reveal variations in the HF trends with latitude and altitude; for example, between 2004 and 2012 HF actually decreased in the Southern Hemisphere below  ∼  35 km. An additional SLIMCAT simulation with repeating meteorology for the year 2000 produces much cleaner trends in HF with minimal variations with latitude and altitude. Therefore, the variations with latitude and altitude in the observed HF trends are due to variability in stratospheric dynamics on the timescale of a few years. Overall, the agreement between observation and model points towards the ongoing success of the Montreal Protocol and the usefulness of HF as a metric for stratospheric fluorine.


Citation: Harrison, J. J., Chipperfield, M. P., Boone, C. D., Dhomse, S. S., Bernath, P. F., Froidevaux, L., Anderson, J., and Russell III, J.: Satellite observations of stratospheric hydrogen fluoride and comparisons with SLIMCAT calculations, Atmos. Chem. Phys., 16, 10501-10519, doi:10.5194/acp-16-10501-2016, 2016.
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Short summary
HF, the dominant stratospheric fluorine reservoir, results from the atmospheric degradation of anthropogenic species such as CFCs, HCFCs, and HFCs. All are strong greenhouse gases, and CFCs and HCFCs deplete stratospheric ozone. We report the comparison of HF global distributions and trends measured by the ACE-FTS and HALOE satellite instruments with the output of SLIMCAT, a chemical transport model. The global HF trends reveal a slowing down in the rate of increase of HF since the 1990s.
HF, the dominant stratospheric fluorine reservoir, results from the atmospheric degradation of...
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