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| Titel |
Retrievals of carbonyl fluoride (COF2) from ACE-FTS and MIPAS spectra and their comparison with SLIMCAT CTM calculations |
| VerfasserIn |
Jeremy Harrison, Shaomin Cai, Anu Dudhia, Martyn Chipperfield, Chris Boone, Peter Bernath |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250092522
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| Publikation (Nr.) |
 EGU/EGU2014-6873.pdf |
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| Zusammenfassung |
| The majority of fluorine in the atmosphere has resulted from the anthropogenic emission of
chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons
(HFCs). Most tropospheric fluorine is present in its emitted ‘organic’ form due to the
molecules having long lifetimes. At the top of the stratosphere most of the fluorine is
present as the ‘inorganic’ product HF, which, due to its extreme stability, is an almost
permanent reservoir of stratospheric fluorine. The second most abundant stratospheric
‘inorganic’ fluorine reservoir is carbonyl fluoride (COF2). The major sources of COF2
are from the atmospheric degradation of CFC-12 (CCl2F2), which is now banned
under the Montreal Protocol, and HCFC-22 (CHF2Cl), the most abundant HCFC
and classed as a transitional substitute under the Montreal Protocol. Although the
amount of CFC-12 in the atmosphere is slowly decreasing, HCFC-22 is still on the
increase. The amounts of COF2, HF, and total fluorine in the atmosphere are all still
increasing.
Vertical profiles of COF2 in the atmosphere have previously been determined from
measurements taken by the Atmospheric Trace MOlecule Spectrometry Experiment
(ATMOS) instrument which flew four times on NASA space shuttles between 1985 and 1994.
Additionally, there have been several studies into the seasonal variability of COF2 columns
above Jungfraujoch using ground-based Fourier transform infrared (FTIR) solar observations.
The concentration of COF2 in the atmosphere slowly increases with altitude up to the middle
of the stratosphere, above which it decreases as photolysis becomes more efficient, leading to
the production of HF.
The use of satellite remote-sensing techniques allows the measurement of COF2
atmospheric abundances with impressive global coverage, and the investigation more fully of
COF2 trends, and seasonal and latitudinal variability. This work presents global distributions
of COF2 using data from two satellite limb instruments: the Atmospheric Chemistry
Experiment Fourier transform spectrometer (ACE-FTS), onboard the SCISAT-1 satellite,
which has been recording atmospheric spectra since 2004, and the Michelson Interferometer
for Passive Atmospheric Sounding (MIPAS) instrument onboard the ENVIronmental
SATellite (Envisat), which has recorded thermal emission atmospheric spectra between 2002
and 2012. The observations are compared with the output of SLIMCAT, a state-of-the-art
three-dimensional chemical transport model (CTM). The model aids in the interpretation of
the COF2 satellite observations, and the comparison provides a validation of emission
inventories and the atmospheric degradation reaction schemes used in the model. |
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