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| Titel |
Assessing the impact of NO2 photo-excitation at global scale |
| VerfasserIn |
Oriol Jorba, Donald Dabdub, Jose Maria Baldasano, Michele Spada, Alba Badia |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250049249
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| Zusammenfassung |
| It is well known that hydroxyl radicals are the single most important oxidant in the
atmosphere and plays an important role in the formation of ozone. Li et al. (2008) recently
reported that the bimolecular reaction of electronically excited NO2 with water can lead to
substantial OH production. Previous results of Crowley and Carl (1997) suggested that the
photo-excitation chemistry of NO2 producing OH radicals is not relevant for atmospheric
applications, presenting a reaction rate for the photo-excited NO2 with H2O an order of
magnitude lower than Li et al. (2008). Such different reaction rates have lead to
several authors to analyze the impact of these new chemistry reactions within air
quality modelling simulations. Wennberg and Dabdub (2008) analyzed the impact of
the new chemistry in the southern California for a summer episode in 1987. The
authors used both reaction rates and reported and enhancement of O3 formation
by as much as 55 ppbv with the chemistry of Li et al. (2008). On the other hand,
Sarwar et al. (2009) argued that the previous results of Wennberg and Dabdub (2008)
were limited to assess the impact of the new chemistry on contemporary emissions.
Sarwar et al. (2009) implemented the new chemistry within CMAQ model and
assess the impact in the U.S during July 2001 and 2002. The authors reported an
increase of O3 production in some urban areas but significantly smaller than those
reported by Wennberg and Dabdub (2008). Finally, Ensberg et al. (2010) have studied
the impacts of the new chemistry on air pollution control strategies in southern
California.
From all the previous results, it is important to analyse the impact of NO2 photo-excited
chemistry on a global scale. It has been shown that the emission regime plays an important
role on the impacts of the chemistry as can be seen from Wennberg and Dabdub (2008),
Sarwar et al. (2009) and Ensberg et al. (2010) results. In the present contribution a
global simulation with an online chemical transport model is analyzed with and
without the new chemistry of photo-excited NO2 with the strong chemistry of Li et al.
(2008) and the limited chemistry of Crowley and Carl (1997). Special attention is
focused on different regimes observed in both urban and rural areas around the
world.
References:
Crowley, J. N. and Carl, S. A., 1997: OH formation in the photoexcitation of NO2
beyond the dissociation threshold in the presence of water vapor, J. Phys. Chem., 101,
4178–4184.
Ensberg, J. J., M. Carreras-Sospedra, and D. Dabdub, 2010: Impacts of electronically
phot-excited NO2 on air pollution control strategies in the South Coast Air Basin of
California, Atmos. Chem. Phys., 10, 1171-1181.
Li, S. P., Matthews, J., and Sinha, A.: Atmospheric hydroxyl radical production from
electronically excited NO2 and H2O, Science, 319, 1657–1660, 2008.
Sarwar, G., Pinder, R.W., Wyat Appel, K., Mathur, R., and A.G. Carlton, 2009:
Examination of the impact of photoexcited NO2 chemistry on regional air quality,
Atmospheric Environment, doi:10.1016/j.atmosenv.2009.09.012
Wennberg, P.O., Dabdub, D., 2008. Rethinking ozone production. Science
319,1624–1625. |
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