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| Titel |
Evidence for heterogeneous chlorine activation in the tropical UTLS |
| VerfasserIn |
M. Hobe, J.-U. Grooß, G. Günther, P. Konopka, I. Gensch, M. Krämer, N. Spelten, A. Afchine, C. Schiller, A. Ulanovsky, N. Sitnikov, G. Shur, V. Yushkov, F. Ravegnani, F. Cairo, A. Roiger, C. Voigt, H. Schlager, R. Weigel, W. Frey, S. Borrmann, R. Müller, F. Stroh |
| 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 ; 11, no. 1 ; Nr. 11, no. 1 (2011-01-12), S.241-256 |
| Datensatznummer |
250009069
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| Publikation (Nr.) |
 copernicus.org/acp-11-241-2011.pdf |
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| Zusammenfassung |
| Airborne in-situ observations of ClO in the tropics were made during the
TROCCINOX (Aracatuba, Brazil, February 2005) and SCOUT-O3 (Darwin,
Australia, November/December 2005) field campaigns. While during most
flights significant amounts of ClO (≈10–20 parts per trillion,
ppt) were present only in aged stratospheric air, instances of enhanced ClO
mixing ratios of up to 40 ppt – significantly exceeding those expected from
gas phase chemistry – were observed in air masses of a more tropospheric
character. Most of these observations are associated with low temperatures
or with the presence of cirrus clouds (often both), suggesting that cirrus
ice particles and/or liquid aerosol at low temperatures may promote
significant heterogeneous chlorine activation in the tropical upper
troposphere lower stratosphere (UTLS). In two case studies, particularly
high levels of ClO observed were reproduced by chemistry simulations only
under the assumption that significant denoxification had occurred in the
observed air. However, to reproduce the ClO observations in these
simulations, O3 mixing ratios higher than observed had to be assumed,
and at least for one of these flights, a significant denoxification is in
contrast to the observed NO levels, suggesting that the coupling of chlorine
and nitrogen compounds in the tropical UTLS may not be completely
understood. |
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