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| Titel |
The evolution of the inorganic fluorine budget since the mid-1980s based on FTIR measurements at northern mid-latitudes |
| VerfasserIn |
Pierre Duchatelet, Wuhu Feng, Martyn Chipperfield, Roland Ruhnke, Peter Bernath, Chris Boone, Kaley Walker, Philippe Demoulin, Emmanuel Mahieu |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250051834
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| Zusammenfassung |
| Fluorine enters the stratosphere principally in the form of CFCs (chlorofluorocarbons, mainly
CFC-12 and CFC-11), HCFCs (hydrochlorofluorocarbons, mainly HCFC-22) and HFCs
(hydrofluorocarbons, mainly HFC-134a) which have been (or are still) widely emitted at
ground level by human activities. In the lower stratosphere, the photolysis of these
halogenated source gases leads to the formation of the two fluorine reservoirs COClF and
COF2. The subsequent photolysis of these two compounds frees F atoms, which principally
react with CH4 and H2O to form the extremely stable HF gas, by far the dominant fluorine
reservoir in the middle and upper stratosphere.
Despite the fact that fluorine does not significantly contribute in stratospheric ozone
depletion, measurements of the concentrations of individual F-containing species in different
altitude ranges of the atmosphere are important as they reflect the amounts of anthropogenic
gases transported into the middle atmosphere as well as their decomposition. Such
measurements also provide insight into the partitioning between major fluorine
source gases (which are potent greenhouse gases) and reservoirs and allows a global
inventory of organic (CFy), inorganic (Fy) and total (FTOT) fluorine burdens to
be monitored as a function of time. Indeed, regular updates of such inventories
are important as the partitioning between F-containing gases in the stratosphere is
continually evolving as emissions of anthropogenic gases from the surface change,
principally as a consequence of the progressive ban on the production of CFCs and
HCFCs adopted by the Montreal Protocol and its subsequent Amendments and
Adjustments.
To complement recent studies regarding fluorine species (Duchatelet et al., 2009, 2010,
2011; Mahieu et al., 2011), this communication presents the time series of the inorganic
fluorine budget Fy over the last twenty-five years, based on HF and COF2 total column
amounts derived from high resolution Fourier transform infrared (FTIR) solar spectra
recorded at Jungfraujoch (46.5Ë N, 8.0Ë E, 3580m asl). A trend analysis of our HF, COF2
and Fy time series is performed and discussed in the context of past and current
emissions of halogenated source gases. Comparisons with model and space data are also
included.
Acknowledgments:
We would like to thank the International Foundation High Altitude Research Stations
Jungfraujoch and Gornergrat (HFSJG, Bern) and the University of Liège for supporting the
facilities needed to perform the observations and their analyses. University of Liège work is
supported primarily by the Belgian Federal Science Policy Office (PRODEX projects
ACE and SECPEA). Additional support by the European Union GEOMON project
(FP6-2006-IP-C036677) is further acknowledged. The Atmospheric Chemistry Experiment
(ACE), also known as SCISAT, is a Canadian-led mission mainly supported by the
Canadian Space Agency and the Natural Sciences and Engineering Research Council of
Canada.
References:
Duchatelet, P., E. Mahieu, R. Ruhnke, et al., An approach to retrieve information on the
carbonyl fluoride (COF2) vertical distributions above Jungfraujoch by FTIR multi-spectrum
multi-window fitting, Atmos. Chem. Phys., 9, 9027-9042, 2009.
Duchatelet P., P. Demoulin, F. Hase, et al., Hydrogen fluoride total and partial column
time series above the Jungfraujoch from long-term FTIR measurements: Impact of the
line-shape model, characterization of the error budget and seasonal cycle, and comparison
with satellite and model data, J. Geophys. Res., 115, D22306, doi10.1029/2010JD014677,
2010.
Duchatelet P., R. Zander, E. Mahieu, et al., First retrievals of carbon tetrafluoride (CF4)
from ground-based FTIR measurements: production and analysis of the two-decadal time
series above the Jungraujoch, this issue, 2011.
Mahieu E., P. Duchatelet, R. Zander, et al., Trend and lifetime of sulfur hexafluoride
(SF6) at mid-latitudes deduced from ACE-FTS occultation measurements, this issue, 2011. |
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