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| Titel |
Long-lived halocarbon trends and budgets from atmospheric chemistry modelling constrained with measurements in polar firn |
| VerfasserIn |
P. Martinerie, E. Nourtier-Mazauric, J.-M. Barnola, W. T. Sturges, D. R. Worton, E. Atlas, L. K. Gohar, K. P. Shine, G. P. Brasseur |
| 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 ; 9, no. 12 ; Nr. 9, no. 12 (2009-06-17), S.3911-3934 |
| Datensatznummer |
250007426
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| Publikation (Nr.) |
 copernicus.org/acp-9-3911-2009.pdf |
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| Zusammenfassung |
| The budgets of seven halogenated gases (CFC-11, CFC-12, CFC-113, CFC-114,
CFC-115, CCl4 and SF6) are studied by comparing measurements in polar
firn air from two Arctic and three Antarctic sites, and simulation results of
two numerical models: a 2-D atmospheric chemistry model and a 1-D firn
diffusion model. The first one is used to calculate atmospheric
concentrations from emission trends based on industrial inventories; the
calculated concentration trends are used by the second one to produce depth
concentration profiles in the firn. The 2-D atmospheric model is validated in
the boundary layer by comparison with atmospheric station measurements, and
vertically for CFC-12 by comparison with balloon and FTIR measurements. Firn
air measurements provide constraints on historical atmospheric concentrations
over the last century. Age distributions in the firn are discussed using a
Green function approach. Finally, our results are used as input to a
radiative model in order to evaluate the radiative forcing of our target
gases. Multi-species and multi-site firn air studies allow to better
constrain atmospheric trends. The low concentrations of all studied gases at
the bottom of the firn, and their consistency with our model results confirm
that their natural sources are small. Our results indicate that the
emissions, sinks and trends of CFC-11, CFC-12, CFC-113, CFC-115 and SF6
are well constrained, whereas it is not the case for CFC-114 and CCl4.
Significant emission-dependent changes in the lifetimes of halocarbons
destroyed in the stratosphere were obtained. Those result from the time
needed for their transport from the surface where they are emitted to the
stratosphere where they are destroyed. Efforts should be made to update and
reduce the large uncertainties on CFC lifetimes. |
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