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| Titel |
Impact of aging mechanism on model simulated carbonaceous aerosols |
| VerfasserIn |
Y. Huang, S. Wu, M. K. Dubey, N. H. F. French |
| 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 ; 13, no. 13 ; Nr. 13, no. 13 (2013-07-04), S.6329-6343 |
| Datensatznummer |
250018736
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| Publikation (Nr.) |
 copernicus.org/acp-13-6329-2013.pdf |
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| Zusammenfassung |
| Carbonaceous aerosols including organic carbon and black
carbon have significant implications for both climate and air quality. In
the current global climate or chemical transport models, a fixed
hydrophobic-to-hydrophilic conversion lifetime for carbonaceous aerosol
(τ) is generally assumed, which is usually around one day. We have
implemented a new detailed aging scheme for carbonaceous aerosols in a
chemical transport model (GEOS-Chem) to account for both the chemical
oxidation and the physical condensation-coagulation effects, where τ
is affected by local atmospheric environment including atmospheric
concentrations of water vapor, ozone, hydroxyl radical and sulfuric acid.
The updated τ exhibits large spatial and temporal variations with the
global average (up to 11 km altitude) calculated to be 2.6 days. The
chemical aging effects are found to be strongest over the tropical regions
driven by the low ozone concentrations and high humidity there. The τ
resulted from chemical aging generally decreases with altitude due to
increases in ozone concentration and decreases in humidity. The
condensation-coagulation effects are found to be most important for the
high-latitude areas, in particular the polar regions, where the τ
values are calculated to be up to 15 days. When both the chemical aging and
condensation-coagulation effects are considered, the total atmospheric
burdens and global average lifetimes of BC, black carbon, (OC, organic carbon) are calculated to increase
by 9% (3%) compared to the control simulation, with considerable
enhancements of BC and OC concentrations in the Southern Hemisphere. Model
evaluations against data from multiple datasets show that the updated aging
scheme improves model simulations of carbonaceous aerosols for some regions,
especially for the remote areas in the Northern Hemisphere. The
improvement helps explain the persistent low model bias for carbonaceous
aerosols in the Northern Hemisphere reported in literature. Further model
sensitivity simulations focusing on the continental outflow of carbonaceous
aerosols demonstrate that previous studies using the old aging scheme could
have significantly underestimated the intercontinental transport of
carbonaceous aerosols. |
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