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| Titel |
Recent trends of inorganic chlorine and halogenated source gases above the Jungfraujoch and Kitt Peak stations derived from high-resolution FTIR solar observations |
| VerfasserIn |
Emmanuel Mahieu, Curtis P. Rinsland, Tom Gardiner, Rodolphe Zander, Philippe Demoulin, Martyn P. Chipperfield, Roland Ruhnke, Linda S. Chiou, Martine De Mazière |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250033529
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| Zusammenfassung |
| The longest series of Fourier Transform Infrared (FTIR) high spectral resolution
solar absorption observations are available from the Jungfraujoch and Kitt Peak
stations, located at 46.5ºN and 30.9ºN, respectively. State-of-the-art interferometers are
operated at these sites within the framework of the Network for the Detection of
Atmospheric Composition Change (NDACC, visit http://www.ndacc.org). These
instruments allow to record spectra on a regular basis, under clear-sky conditions,
using a suite of optical filters which altogether cover the 2 to 16 micron spectral
range.
Numerous absorption features characterized in the HITRAN compilations (e.g. Rothman
et al., 2008) are encompassed in this mid-infrared region. Their analyses with either the
SFIT-1 or SFIT-2 algorithm allow retrieving total columns of the target gases. Moreover,
information on their distribution with altitude can generally be derived when using SFIT-2
which implements the Optimal Estimation Method of Rodgers (1990). Among the two dozen
gases of atmospheric interest accessible to the ground-based FTIR technique, we have
selected here a suite of long-lived halogenated species: HCl, ClONO2, CCl2F2, CCl3F,
CHClF2, CCl4 and SF6.
Time series available from the two sites will be presented, compared and critically
discussed. In particular, changes in the abundances of theses gases since the peak in
inorganic chlorine (Cly, which occurred in 1996-1997) and their intra-annual variability
will be characterized with a statistical tool using bootstrap resampling (Gardiner et
al., 2008). Trends and their associated uncertainties will be reported and put into
perspective with the phase-out regulations of the production of ozone depleting
substances adopted and implemented by the Montreal Protocol, its Amendments and
Adjustments.
For instance, the trends affecting the reservoir species HCl, ClONO2, and their
summation which is a good proxy of the total inorganic chlorine, have been calculated using
all available daily mean measurements from January 1996 onwards. The following values
were obtained for Jungfraujoch, when using 1996 as the reference year: -0.90±0.10%/yr for
HCl, -0.92±0.26 %/yr for ClONO2, and -0.96±0.14 %/yr for Cly; in all cases, the
uncertainties define the 95% confidence interval around the trend values. For Kitt Peak
(covering 1977-2009 but with far fewer measurements than from Jungfraujoch), the
corresponding trends are: -0.55±0.34 %/yr for HCl, -1.27±0.84 %/yr for ClONO2 and
-0.61±0.51 %/yr for Cly, they are statistically consistent with the Jungfraujoch rates of
decrease.
Further trend data will be presented at the EGU General Assembly while supplementary
information on Jungfraujoch results will be available from communications at the same
meeting by Duchatelet et al. (2010), Lejeune et al (2010) and Rinsland et al (2010).
Comparisons with model data are also foreseen.
Acknowledgments
The University of Liège contribution to present work has primarily been supported by the
AGACC and SECPEA projects funded by the Belgian Federal Science Policy Office
(BELSPO), Brussels. We further acknowledge the support of the GEOMon European project.
Work at the NASA Langley Research Center was supported by NASA’s Upper Atmospheric
Chemistry and Modeling Program (ACMAP).
References
Duchatelet et al., Updating hydrogen fluoride (HF) FTIR time series above Jungfraujoch:
comparison of two retrieval algorithms and impact of line shape models, this issue,
2010.
Gardiner, T., A. Forbes, M. De Mazière et al., Trend analysis of greenhouse gases over
Europe measured by a network of ground-based remote FTIR instruments, Atmos. Chem.
Phys., 8, 6719-6727, 2008.
Lejeune et al., Optimized approach to retrieve information on the Tropospheric and
Stratospheric Carbonyl Sulfide (OCS) vertical distributions above Jungfraujoch from
high-resolution FTIR solar spectra, this issue, 2010.
Rinsland et al., Long-term trend of carbon tetrachloride (CCl4) from ground-based
high-resolution infrared solar spectra recorded at the Jungfraujoch, this issue, 2010.
Rodgers, C.D., Characterisation and error analysis of profiles derived from remote
sensing measurements, J. Geophys Res., 95, 5587-5595, 1990.
Rothman, L.S., I.E. Gordon, A. Barbe et al., The HITRAN 2008 molecular
spectroscopic database, J. Quant. Spectrosc. Radiat. Transfer, 110, 533-572, 2008. |
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