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| Titel |
Stratospheric lifetimes of CFC-12, CCl4, CH4, CH3Cl and N2O from measurements made by the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) |
| VerfasserIn |
A. T. Brown, C. M. Volk, M. R. Schoeberl, C. D. Boone, P. F. Bernath |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 14 ; Nr. 13, no. 14 (2013-07-23), S.6921-6950 |
| Datensatznummer |
250018772
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| Publikation (Nr.) |
 copernicus.org/acp-13-6921-2013.pdf |
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| Zusammenfassung |
| Long lived halogen-containing compounds are important atmospheric
constituents since they can act both as a source of chlorine radicals, which
go on to catalyse ozone loss, and as powerful greenhouse gases. The long-term
impact of these species on the ozone layer is dependent on their
stratospheric lifetimes. Using observations from the Atmospheric Chemistry
Experiment Fourier Transform Spectrometer (ACE-FTS) we present calculations
of the stratospheric lifetimes of CFC-12, CCl4, CH4, CH3Cl
and N2O. The lifetimes were calculated using the slope of the
tracer–tracer correlation of these species with CFC-11 at the tropopause.
The correlation slopes were corrected for the changing atmospheric
concentrations of each species based on age of air and CFC-11
measurements from samples taken aboard the Geophysica aircraft – along with
the effective linear trend of the volume mixing ratio (VMR) from tropical
ground based AGAGE (Advanced Global Atmospheric Gases Experiment) sites.
Stratospheric lifetimes were calculated using a
CFC-11 lifetime of 45 yr. These calculations produced values of 113 +
(−) 26 (18) yr (CFC-12), 35 + (−) 11 (7) yr (CCl4), 69 + (−)
65 (23) yr (CH3Cl), 123 + (−) 53 (28) yr (N2O) and 195 +
(−) 75 (42) yr (CH4). The errors on these values are the
weighted 1σ non-systematic errors. Systematic errors were estimated
by recalculating lifetimes using VMRs which had been modified to reflect
differences between ACE-FTS retrieved VMRs and those from other instruments.
The results of these calculations, including systematic errors, were as
follows: 113 + (−) 32 (20) for CFC-12, 123 + (−) 83 (35) for N2O, 195
+ (−) 139 (57) for CH4, 35 + (−) 14 (8) for CCl4 and 69 + (−)
2119 (34) yr for CH3Cl. For CH3Cl & CH4 this represents the
first calculation of the stratospheric lifetime using data from a space
based instrument. |
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