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| Titel |
Simulation of semi-explicit mechanisms of SOA formation from glyoxal in aerosol in a 3-D model |
| VerfasserIn |
C. Knote, A. Hodzic, J. L. Jimenez, R. Volkamer, J. J. Orlando, S. Baidar, J. Brioude, J. Fast, D. R. Gentner, A. H. Goldstein, P. L. Hayes, W. B. Knighton, H. Oetjen, A. Setyan, H. Stärk, R. Thalman, G. Tyndall, R. Washenfelder, E. Waxman, Q. Zhang |
| 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 ; 14, no. 12 ; Nr. 14, no. 12 (2014-06-24), S.6213-6239 |
| Datensatznummer |
250118829
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| Publikation (Nr.) |
 copernicus.org/acp-14-6213-2014.pdf |
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| Zusammenfassung |
New pathways to form secondary organic aerosol (SOA) have been
postulated recently. Glyoxal, the smallest dicarbonyl, is one of the
proposed precursors. It has both anthropogenic and biogenic
sources, and readily partitions into the aqueous phase of cloud
droplets and deliquesced particles where it undergoes both reversible
and irreversible chemistry. In this work we extend the regional
scale chemistry transport model WRF-Chem to include detailed
gas-phase chemistry of glyoxal formation as well as
a state-of-the-science module describing its partitioning and
reactions in the aerosol aqueous-phase. A comparison of several
proposed mechanisms is performed to quantify the relative importance
of different formation pathways and their regional variability. The
CARES/CalNex campaigns over California in summer 2010 are used as
case studies to evaluate the model against observations. A month-long
simulation over the continental United States (US) enables us to extend
our results to the continental scale.
In all simulations over California, the Los Angeles (LA) basin was found to be
the hot spot for SOA formation from glyoxal, which contributes between 1%
and 15% of the model SOA depending on the mechanism used. Our results
indicate that a mechanism based only on a reactive (surface limited) uptake
coefficient leads to higher SOA yields from glyoxal compared to a more
detailed description that considers aerosol phase state and chemical
composition. In the more detailed simulations, surface uptake is found to give
the highest SOA mass yields compared to a volume process and reversible
formation. We find that the yields of the latter are limited by the
availability of glyoxal in aerosol water, which is in turn controlled by an
increase in the Henry's law constant depending on salt concentrations
("salting-in"). A time dependence in this increase prevents substantial
partitioning of glyoxal into aerosol water at high salt concentrations. If
this limitation is removed, volume pathways contribute > 20% of
glyoxal-SOA mass, and the total mass formed (5.8% of total SOA in the LA
basin) is about a third of the simple uptake coefficient formulation without
consideration of aerosol phase state and composition. Results from the
continental US simulation reveal the much larger potential to form
glyoxal-SOA over the eastern continental US. Interestingly, the low concentrations
of glyoxal-SOA over the western continental US are not due to the lack of a
potential to form glyoxal-SOA here. Rather these small glyoxal-SOA
concentrations reflect dry conditions and high salt concentrations, and the
potential to form SOA mass here will strongly depend on the water
associated
with particles. |
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