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| Titel |
Improvements of organic aerosol representations and their effects in large-scale atmospheric models |
| VerfasserIn |
H. Tost, K. J. Pringle |
| 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 ; 12, no. 18 ; Nr. 12, no. 18 (2012-09-26), S.8687-8709 |
| Datensatznummer |
250011473
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| Publikation (Nr.) |
 copernicus.org/acp-12-8687-2012.pdf |
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| Zusammenfassung |
Organics dominate the composition of the atmospheric aerosol,
especially in the fine mode, influencing some of its characteristics
such as the hygroscopicity, which is of climatic relevance for the
Earth system. This study targets an improvement in the description
of organic aerosols suitable for large-scale modelling, making use
of recent developments based on laboratory and field measurements.
In addition to the organic mass and particle number distribution,
the proposed method keeps track of the oxidation state of the
aerosol based on the OH exposure time, describing some of its
chemical characteristics. This study presents the application of
the method in a global chemistry climate model, investigates the
sensitivity to process formulations and emission assignments,
provides a comparison with observations and analyses the climate
impact.
Even though the organic aerosol mass distribution is hardly affected
by the new formulation, it shows impacts (regionally of the order of
10 % to 20 %) on parameters directly influencing climate via the
direct and indirect aerosol effects. Furthermore, the global
distribution of the organic O:C ratio is analysed in detail, leading
to different regimes in the oxidation state: low O:C ratios over the
tropical continents due to small OH concentrations caused by OH
depletion in chemical reactions, and enhanced oxidation states over
the tropical oceans based on less OH scavengers and at high
altitudes due to longer atmospheric residence time. Due to the
relation between O:C ratio and the aerosol hygroscopicity the ageing
results in a more physically and chemically consistent description of
aerosol water uptake by the organic aerosol. In comparison with
observations reasonable agreement for the O:C ratio within the limits
of a global model of the simulations is achieved. |
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