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| Titel |
Detailed comparisons of airborne formaldehyde measurements with box models during the 2006 INTEX-B and MILAGRO campaigns: potential evidence for significant impacts of unmeasured and multi-generation volatile organic carbon compounds |
| VerfasserIn |
A. Fried, C. Cantrell, J. Olson, J. H. Crawford, P. Weibring, J. Walega, D. Richter, W. Junkermann, R. Volkamer, R. Sinreich, B. G. Heikes, D. O'Sullivan, D. R. Blake, N. Blake, S. Meinardi, E. Apel, A. Weinheimer, D. Knapp, A. Perring, R. C. Cohen, H. Fuelberg, R. E. Shetter, S. R. Hall, K. Ullmann, W. H. Brune, J. Mao, X. Ren, L. G. Huey, H. B. Singh, J. W. Hair, D. Riemer, G. Diskin, G. Sachse |
| 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. 22 ; Nr. 11, no. 22 (2011-11-30), S.11867-11894 |
| Datensatznummer |
250010225
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| Publikation (Nr.) |
 copernicus.org/acp-11-11867-2011.pdf |
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| Zusammenfassung |
| Detailed comparisons of airborne CH2O measurements acquired by tunable
diode laser absorption spectroscopy with steady state box model calculations
were carried out using data from the 2006 INTEX-B and MILARGO campaign in
order to improve our understanding of hydrocarbon oxidation processing. This
study includes comparisons over Mexico (including Mexico City), the Gulf of
Mexico, parts of the continental United States near the Gulf coast, as well
as the more remote Pacific Ocean, and focuses on comparisons in the boundary
layer. Select previous comparisons in other campaigns have highlighted some
locations in the boundary layer where steady state box models have tended to
underpredict CH2O, suggesting that standard steady state modeling
assumptions might be unsuitable under these conditions, and pointing to a
possible role for unmeasured hydrocarbons and/or additional primary emission
sources of CH2O. Employing an improved instrument, more detailed
measurement-model comparisons with better temporal overlap, up-to-date
measurement and model precision estimates, up-to-date rate constants, and
additional modeling tools based on both Lagrangian and Master Chemical
Mechanism (MCM) runs, we have explained much of the disagreement between
observed and predicted CH2O as resulting from non-steady-state
atmospheric conditions in the vicinity of large pollution sources, and have
quantified the disagreement as a function of plume lifetime
(processing time). We show that in the near field (within ~4 to 6 h of
the source), steady-state models can either over-or-underestimate
observations, depending on the predominant non-steady-state influence. In
addition, we show that even far field processes (10–40 h) can be influenced
by non-steady-state conditions which can be responsible for CH2O model
underestimations by ~20%. At the longer processing times in the 10
to 40 h range during Mexico City outflow events, MCM model calculations,
using assumptions about initial amounts of high-order NMHCs, further indicate
the potential importance of CH2O produced from unmeasured and
multi-generation hydrocarbon oxidation compounds, particularly methylglyoxal,
3-hydroxypropanal, and butan-3-one-al. |
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