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| Titel |
HOx regeneration in isoprene oxidation: global model evaluation of newly-proposed reaction sequences |
| VerfasserIn |
Jean-Francois Müller, Jozef Peeters, Jenny Stavrakou |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250033607
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| Zusammenfassung |
| There is now overwhelming evidence that the traditional isoprene chemical oxidation
mechanism used in CTMs requires substantial revision. Lelieveld et al. (Nature, 2008)
showed that strong OH regeneration must be invoked in order to explain observed HOx levels
in isoprene-rich, pristine conditions, and suggested that it occurs through the reactions
of isoprene peroxy radicals with HO2. Paulot et al. (Science, 2009) showed in a
laboratory study that the OH-reaction of isoprene hydroperoxides generates OH
along with dihydroxy epoxides possibly contributing to secondary organic aerosol
formation. However, measurement campaigns at mid-latitudes indicate that HOx
regeneration occurs even at mid-latitudes (Hofzumahaus et al., Science, 2009;
Ren et al., J.Geophys.Res., 2008) where isoprene peroxy radicals are expected to
react mostly with NO. A likely explanation is provided by the theoretical study of
Peeters et al. (Phys.Chem.Chem.Phys., 2009), which showed that isomerization
reactions of specific isomer/conformer peroxy radicals from isoprene lead to the
formation of HOx radicals and photolabile hydroperoxy aldehydes (denoted HPALDs),
at rates such that the traditional reactions of the isoprene peroxy radicals (with
NO and HO2) are outrun in most non-urban atmospheric conditions. We present a
detailed global modelling study aiming at quantifying the impact of the new reactions
proposed by Paulot et al. and Peeters et al. on the global tropospheric composition. The
calculated concentrations of key compounds will be evaluated against measurement
campaigns at Tropical (e.g. GABRIEL) and mid-latitudes (INTEX-A, PROPHET), and
sensitivity simulations wil be performed to estimate the remaining uncertainties. |
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