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| Titel |
Characterization of non-methane hydrocarbons in Asian summer monsoon outflow observed by the CARIBIC aircraft |
| VerfasserIn |
A. K. Baker, T. J. Schuck, F. Slemr, P. Velthoven, A. Zahn, C. A. M. Brenninkmeijer |
| 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. 2 ; Nr. 11, no. 2 (2011-01-18), S.503-518 |
| Datensatznummer |
250009180
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| Publikation (Nr.) |
 copernicus.org/acp-11-503-2011.pdf |
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| Zusammenfassung |
| Between April and December 2008 the CARIBIC commercial aircraft conducted
monthly measurement flights between Frankfurt, Germany and Chennai, India.
These flights covered the period of the Asian summer monsoon (June–September),
during which enhancements in a number of atmospheric species were observed
in the upper troposphere over southwestern Asia. In addition to in situ
measurements of trace gases and aerosols, whole air samples were collected
during the flights, and these were subsequently analyzed for a suite of
trace gases that included a number of C2–C8 non-methane
hydrocarbons. Non-methane hydrocarbons are relatively short-lived compounds
and the large enhancements in their mixing ratios in the upper troposphere
over southwestern Asia during the monsoon, sometimes more than double their
spring and fall means, provides qualitative evidence for the influence of
convectively uplifted boundary layer air. The particularly large
enhancements of the combustion tracers benzene and ethyne, along with the
similarity of their ratios with carbon monoxide and emission ratios from the
burning of household biofuels, indicate a strong influence of biofuel
burning to NMHC emissions in this region. Conversely, the ratios of ethane
and propane to carbon monoxide, along with the ratio between i-butane and
n-butane, indicate a significant source of these compounds from the use of
fossil fuels, and comparison to previous campaigns suggests that this source
could be increasing. Photochemical aging patterns of NMHCs showed that the
CARIBIC samples were collected in two distinctly different regions of the
monsoon circulation: a southern region where air masses had been recently
influenced by low level contact and a northern region, where air parcels had
spent substantial time in transit in the upper troposphere before being
probed. Estimates of age using ratios of individual NMHCs have ranges of 3–6
days in the south and 9–12 days in the north. |
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