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| Titel |
Understanding the impact of recent advances in isoprene photooxidation on simulations of regional air quality |
| VerfasserIn |
Y. Xie, F. Paulot, W. P. L. Carter, C. G. Nolte, D. J. Luecken, W. T. Hutzell, P. O. Wennberg, R. C. Cohen, R. W. Pinder |
| 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. 16 ; Nr. 13, no. 16 (2013-08-27), S.8439-8455 |
| Datensatznummer |
250085651
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| Publikation (Nr.) |
 copernicus.org/acp-13-8439-2013.pdf |
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| Zusammenfassung |
| The CMAQ (Community Multiscale Air Quality) us model in combination with observations for INTEX-NA/ICARTT (Intercontinental Chemical Transport Experiment–North America/International Consortium for Atmospheric Research on Transport and Transformation) 2004 are
used to evaluate recent advances in isoprene oxidation chemistry and provide
constraints on isoprene nitrate yields, isoprene nitrate lifetimes, and
NOx recycling rates. We incorporate recent advances in isoprene
oxidation chemistry into the SAPRC-07 chemical mechanism within the US EPA
(United States Environmental Protection Agency)
CMAQ model. The results show improved
model performance for a range of species compared against aircraft
observations from the INTEX-NA/ICARTT 2004 field campaign. We further
investigate the key processes in isoprene nitrate chemistry and evaluate the
impact of uncertainties in the isoprene nitrate yield, NOx
(NOx = NO + NO2) recycling efficiency, dry deposition velocity,
and RO2 + HO2 reaction rates. We focus our examination on the
southeastern United States, which is impacted by both abundant isoprene
emissions and high levels of anthropogenic pollutants. We find that NOx
concentrations increase by 4–9% as a result of reduced removal by
isoprene nitrate chemistry. O3 increases by 2 ppbv as a result of
changes in NOx. OH concentrations increase by 30%, which can be
primarily attributed to greater HOx production. We find that the model
can capture observed total alkyl and multifunctional nitrates (∑ANs)
and their relationship with O3 by assuming either an isoprene nitrate
yield of 6% and daytime lifetime of 6 hours or a yield of 12% and
lifetime of 4 h. Uncertainties in the isoprene nitrates can impact ozone
production by 10% and OH concentrations by 6%. The uncertainties in
NOx recycling efficiency appear to have larger effects than
uncertainties in isoprene nitrate yield and dry deposition velocity. Further
progress depends on improved understanding of isoprene oxidation pathways,
the rate of NOx recycling from isoprene nitrates, and the fate of the
secondary, tertiary, and further oxidation products of isoprene. |
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