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| Titel |
A secondary organic aerosol formation model considering successive oxidation aging and kinetic condensation of organic compounds: global scale implications |
| VerfasserIn |
F. Yu |
| 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 ; 11, no. 3 ; Nr. 11, no. 3 (2011-02-08), S.1083-1099 |
| Datensatznummer |
250009293
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| Publikation (Nr.) |
 copernicus.org/acp-11-1083-2011.pdf |
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| Zusammenfassung |
| The widely used two-product secondary organic aerosol
(SOA) formation model has been extended in this study to consider the
volatility changes of secondary organic gases (SOG) arising from the aging
process as well as the kinetic condensation of low volatile SOG (LV-SOG). In
addition to semi-volatile SOG (SV-SOG) with saturation vapor pressure at
290 K (C*290) in the range of ~3 ppt–3 ppb and medium-volatile SOG (MV-SOG)
with C*290
in the range of ~0.3–300 ppb, we add a third component
representing LV-SOG with C*290
below ~3 ppt and design a scheme to transfer MV-SOG to SV-SOG and
SV-SOG to LV-SOG associated with oxidation aging. This extended SOA
formation model has been implemented in a global aerosol model (GEOS-Chem)
and the co-condensation of H2SO4 and LV-SOG on pre-existing
particles is explicitly simulated. We show that, over many parts of the
continents, LV-SOG concentrations are generally a factor of ~2–20
higher than those of H2SO4 and the kinetic condensation of LV-SOG
significantly enhances particle growth rates. Comparisons of the simulated
and observed evolution of particle size distributions at a boreal forest
site (Hyytiälä, Finland) clearly show that LV-SOG condensation is
critical in order to bring the simulations closer to the observations. With
the new SOA formation scheme, annual mean SOA mass increases by a factor of
2–10 in many parts of the boundary layer and reaches above 0.5 μg m−3
in most parts of the main continents, improving the agreement with
aerosol mass spectrometer (AMS) SOA measurements. While the new scheme
generally decreases the concentration of condensation nuclei larger than 10 nm by 3–30%
in the lower boundary layer as a result of enhanced surface
area and reduced nucleation rates, it substantially increases the
concentration of cloud condensation nuclei at a water supersaturation ratio
of 0.2%, ranging from ~5–20% over a large fraction of oceans and
high latitude continents to more than 50% over some parts of South
America, Australia, and Indonesia. Our study highlights the importance for
global aerosol models to explicitly account for the oxidation aging of SOGs
and their contribution to particle growth. |
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