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| Titel |
Biogenic VOC oxidation and organic aerosol formation in an urban nocturnal boundary layer: aircraft vertical profiles in Houston, TX |
| VerfasserIn |
S. S. Brown, W. P. Dubé, R. Bahreini, A. M. Middlebrook, C. A. Brock, C. Warneke, J. A. de Gouw, R. A. Washenfelder, E. Atlas, J. Peischl, T. B. Ryerson, J. S. Holloway, J. P. Schwarz, R. Spackman, M. Trainer, D. D. Parrish, F. C. Fehshenfeld, A. R. Ravishankara |
| 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 ; 13, no. 22 ; Nr. 13, no. 22 (2013-11-22), S.11317-11337 |
| Datensatznummer |
250085829
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| Publikation (Nr.) |
 copernicus.org/acp-13-11317-2013.pdf |
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| Zusammenfassung |
| Organic compounds are a large component of aerosol mass, but organic aerosol
(OA) sources remain poorly characterized. Recent model studies have
suggested nighttime oxidation of biogenic hydrocarbons as a potentially
large OA source, but analysis of field measurements to test these
predictions is sparse. We present nighttime vertical profiles of nitrogen
oxides, ozone, VOCs and aerosol composition measured during low approaches
of the NOAA P-3 aircraft to airfields in Houston, TX. This region has large
emissions of both biogenic hydrocarbons and nitrogen oxides. The latter
category serves as a source of the nitrate radical, NO3, a key nighttime
oxidant. Biogenic VOCs (BVOC) and urban pollutants were concentrated within
the nocturnal boundary layer (NBL), which varied in depth from 100–400 m.
Despite concentrated NOx at low altitude, ozone was never titrated to
zero, resulting in rapid NO3 radical production rates of 0.2–2.7 ppbv h−1 within the NBL. Monoterpenes and isoprene were frequently present
within the NBL and underwent rapid oxidation (up to 1 ppbv h−1),
mainly by NO3 and to a lesser extent O3. Concurrent enhancement in
organic and nitrate aerosol on several profiles was consistent with primary
emissions and with secondary production from nighttime BVOC oxidation, with
the latter equivalent to or slightly larger than the former. Some profiles
may have been influenced by biomass burning sources as well, making
quantitative attribution of organic aerosol sources difficult. Ratios of
organic aerosol to CO within the NBL ranged from 14 to 38 μg m−3
OA/ppmv CO. A box model simulation incorporating monoterpene emissions,
oxidant formation rates and monoterpene SOA yields suggested overnight OA
production of 0.5 to 9 μg m−3. |
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