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| Titel |
The very short-lived ozone depleting substance CHBr3 (bromoform): revised UV absorption spectrum, atmospheric lifetime and ozone depletion potential |
| VerfasserIn |
D. K. Papanastasiou, S. A. McKeen, J. B. Burkholder |
| 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 ; 14, no. 6 ; Nr. 14, no. 6 (2014-03-26), S.3017-3025 |
| Datensatznummer |
250118524
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| Publikation (Nr.) |
 copernicus.org/acp-14-3017-2014.pdf |
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| Zusammenfassung |
| CHBr3 (bromoform) is a short-lived atmospheric trace compound that is
primarily of natural origin and is a source of reactive bromine in both the
troposphere and stratosphere. Estimating the overall atmospheric impact of
CHBr3 and its transport to the stratosphere requires a thorough
understanding of its atmospheric loss processes, which are primarily UV
photolysis and reaction with the OH radical. In this study, UV absorption
cross sections, σ (λ ,T), for CHBr3 were measured at
wavelengths between 300 and 345 nm at temperatures between 260 and 330 K
using cavity ring-down spectroscopy. The present results are compared with
currently recommended values for use in atmospheric models, and the
discrepancies are discussed. A parameterization of the CHBr3 UV
spectrum for use in atmospheric models is developed, and illustrative
photolysis rate calculations are presented to highlight the impact of the
revised σ (λ, T) values on its calculated local lifetimes.
For example, the photolysis rate in the tropical region obtained with the present
spectral data is 10–15% lower (longer lifetime) than obtained using
currently recommended cross section values. Seasonally dependent ozone
depletion potentials (ODPs) for CHBr3 emitted in the Indian
sub-continent were calculated to be 0.10, 0.34, 0.72, and 0.23 (winter,
spring, summer, fall) using the semi-empirical relationship of Brioude et
al. (2010). |
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