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| Titel |
Reassessing the ratio of glyoxal to formaldehyde as an indicator of hydrocarbon precursor speciation |
| VerfasserIn |
J. Kaiser, G. M. Wolfe, K. E. Min, S. S. Brown, C. C. Miller, D. J. Jacob, J. A. deGouw, M. Graus, T. F. Hanisco, J. Holloway, J. Peischl, I. B. Pollack, T. B. Ryerson, C. Warneke, R. A. Washenfelder, F. N. Keutsch |
| 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 ; 15, no. 13 ; Nr. 15, no. 13 (2015-07-13), S.7571-7583 |
| Datensatznummer |
250119889
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| Publikation (Nr.) |
 copernicus.org/acp-15-7571-2015.pdf |
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| Zusammenfassung |
| The yield of formaldehyde (HCHO) and glyoxal (CHOCHO) from oxidation of
volatile organic compounds (VOCs) depends on precursor VOC structure and the
concentration of NOx (NOx = NO + NO2). Previous work has
proposed that the ratio of CHOCHO to HCHO (RGF) can be used as an
indicator of precursor VOC speciation, and absolute concentrations of the
CHOCHO and HCHO as indicators of NOx. Because this metric is measurable
by satellite, it is potentially useful on a global scale; however, absolute
values and trends in RGF have differed between satellite and
ground-based observations. To investigate potential causes of previous
discrepancies and the usefulness of this ratio, we present measurements of
CHOCHO and HCHO over the southeastern United States (SE US) from the 2013 SENEX
(Southeast Nexus) flight campaign, and compare these measurements with OMI (Ozone Monitoring
Instrument) satellite
retrievals. High time-resolution flight measurements show that high RGF
is associated with monoterpene emissions, low RGF is associated with
isoprene oxidation, and emissions associated with oil and gas production can
lead to small-scale variation in regional RGF. During the summertime in
the SE US, RGF is not a reliable diagnostic of anthropogenic VOC
emissions, as HCHO and CHOCHO production are dominated by isoprene
oxidation. Our results show that the new CHOCHO retrieval algorithm reduces
the previous disagreement between satellite and in situ RGF
observations. As the absolute values and trends in RGF observed during
SENEX are largely reproduced by OMI observations, we conclude that
satellite-based observations of RGF can be used alongside knowledge of
land use as a global diagnostic of dominant hydrocarbon speciation. |
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