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| Titel |
Global modeling of SOA: the use of different mechanisms for aqueous-phase formation |
| VerfasserIn |
G. Lin, S. Sillman, J. E. Penner, A. Ito |
| 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. 11 ; Nr. 14, no. 11 (2014-06-04), S.5451-5475 |
| Datensatznummer |
250118768
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| Publikation (Nr.) |
 copernicus.org/acp-14-5451-2014.pdf |
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| Zusammenfassung |
| There is growing interest in the formation of secondary organic aerosol (SOA)
through condensed aqueous-phase reactions. In this study, we use a global
model (IMPACT) to investigate the potential formation of SOA in the aqueous
phase. We compare results from several multiphase process schemes with
detailed aqueous-phase reactions to schemes that use a first-order
gas-to-particle formation rate based on uptake coefficients. The predicted
net global SOA production rate in cloud water ranges from 13.1 Tg yr−1
to 46.8 Tg yr−1 while that in aerosol water ranges from
−0.4 Tg yr−1 to 12.6 Tg yr−1. The predicted global burden of
SOA formed in the aqueous phase ranges from 0.09 Tg to 0.51 Tg. A
sensitivity test to investigate two representations of cloud water content
from two global models shows that increasing cloud water by an average factor
of 2.7 can increase the net SOA production rate in cloud water by a factor of 4 at
low altitudes (below approximately 900 hPa). We also investigated the
importance of including dissolved Fe chemistry in cloud water aqueous reactions.
Adding these reactions increases the formation rate of aqueous-phase OH by a
factor of 2.6 and decreases the amount of global aqueous SOA formed by
31%. None of the mechanisms discussed here is able to provide a best fit
for all observations. Rather, the use of an uptake coefficient method for
aerosol water and a multi-phase scheme for cloud water provides the best fit
in the Northern Hemisphere and the use of multiphase process scheme for
aerosol and cloud water provides the best fit in the tropics. The model with
Fe chemistry underpredicts oxalate measurements in all regions. Finally,
the comparison of oxygen-to-carbon (O / C) ratios estimated in the model
with those estimated from measurements shows that the modeled SOA has a
slightly higher O / C ratio than the observed SOA for all cases. |
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