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| Titel |
ClOOCl photolysis at high solar zenith angles: analysis of the RECONCILE self-match flight |
| VerfasserIn |
O. Sumińska-Ebersoldt, R. Lehmann, T. Wegner, J.-U. Grooß, E. Hösen, R. Weigel, W. Frey, S. Griessbach, V. Mitev, C. Emde, C. M. Volk, S. Borrmann, M. Rex, F. Stroh, M. Hobe |
| 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 ; 12, no. 3 ; Nr. 12, no. 3 (2012-02-02), S.1353-1365 |
| Datensatznummer |
250010634
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| Publikation (Nr.) |
 copernicus.org/acp-12-1353-2012.pdf |
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| Zusammenfassung |
| The photolysis rate constant of dichlorine peroxide (ClOOCl, ClO dimer) JClOOCl
is a critical parameter in catalytic cycles destroying ozone (O3) in the polar stratosphere.
In the atmospherically relevant wavelength region (λ > 310 nm), significant
discrepancies between laboratory measurements of ClOOCl absorption cross sections and
spectra cause a large uncertainty in JClOOCl. Previous investigations of
the consistency of published JClOOCl with atmospheric observations of chlorine
monoxide (ClO) and ClOOCl have focused on the photochemical equilibrium between ClOOCl
formation and photolysis, and thus could only constrain the ratio of JClOOCl
over the ClOOCl formation rate constant krec. Here, we constrain the atmospherically
effective JClOOCl independent of krec, using ClO measured in the
same air masses before and directly after sunrise during an aircraft flight that was part of
the RECONCILE field campaign in the winter 2010 from Kiruna, Sweden. Over sunrise, when the
ClO/ClOOCl system comes out of thermal equilibrium and the influence of the ClO recombination
reaction is negligible, the increase in ClO concentrations is significantly faster than expected
from JClOOCl based on the absorption spectrum proposed by Pope et al. (2007),
but does not warrant cross sections larger than recently published values by Papanastasiou et al. (2009).
In particular, the existence of a significant ClOOCl absorption band longwards of 420 nm
is not supported by our observations. The observed night-time ClO would not be consistent
with a ClO/ClOOCl thermal equilibrium constant significantly higher than the one proposed by Plenge et al. (2005). |
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