 |
| Titel |
Modeling secondary organic aerosol formation through cloud processing of organic compounds |
| VerfasserIn |
J. Chen, R. J. Griffin, A. Grini, P. Tulet |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 7, no. 20 ; Nr. 7, no. 20 (2007-10-17), S.5343-5355 |
| Datensatznummer |
250005230
|
| Publikation (Nr.) |
 copernicus.org/acp-7-5343-2007.pdf |
|
|
|
|
|
| Zusammenfassung |
| Interest in the potential formation of secondary organic aerosol (SOA)
through reactions of organic compounds in condensed aqueous phases is
growing. In this study, the potential formation of SOA from irreversible
aqueous-phase reactions of organic species in clouds was investigated. A new
proposed aqueous-phase chemistry mechanism (AqChem) is coupled with the
existing gas-phase Caltech Atmospheric Chemistry Mechanism (CACM) and the
Model to Predict the Multiphase Partitioning of Organics (MPMPO) that
simulate SOA formation. AqChem treats irreversible organic reactions that
lead mainly to the formation of carboxylic acids, which are usually less
volatile than the corresponding aldehydic compounds. Zero-dimensional model
simulations were performed for tropospheric conditions with clouds present
for three consecutive hours per day. Zero-dimensional model simulations show
that 48-h average SOA formation is increased by 27% for a rural
scenario with strong monoterpene emissions and 7% for an urban scenario
with strong emissions of aromatic compounds, respectively, when irreversible
organic reactions in clouds are considered. AqChem was also incorporated
into the Community Multiscale Air Quality Model (CMAQ) version 4.4 with
CACM/MPMPO and applied to a previously studied photochemical episode
(3–4 August 2004) focusing on the eastern United States. The CMAQ study indicates
that the maximum contribution of SOA formation from irreversible reactions
of organics in clouds is 0.28 μg m−3 for 24-h average
concentrations and 0.60 μg m−3 for one-hour average concentrations
at certain locations. On average, domain-wide surface SOA predictions for
the episode are increased by 9% when irreversible, in-cloud processing
of organics is considered. Because aldehydes of carbon number greater than four
are assumed to convert fully to the corresponding carboxylic acids upon reaction
with OH in cloud droplets and this assumption may overestimate carboxylic acid
formation from this reaction route, the present study provides an upper bound
estimate of SOA formation via this pathway. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|