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| Titel |
Cloud processing, cloud evaporation and Angström exponent |
| VerfasserIn |
G.-J. Roelofs, V. Kamphuis |
| 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 ; 9, no. 1 ; Nr. 9, no. 1 (2009-01-07), S.71-80 |
| Datensatznummer |
250006630
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| Publikation (Nr.) |
 copernicus.org/acp-9-71-2009.pdf |
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| Zusammenfassung |
| With a cloud parcel model we investigate how cloud processing and cloud
evaporation modify the size distribution and the Angström exponent of an
aerosol population. Our study provides a new explanation for the observed
variability of the aerosol optical thickness and Angström exponent in
the vicinity of clouds. Cloud processing causes a decrease of aerosol
particle concentrations, relatively most efficiently in the coarse mode, and
reduces the relative dispersion of the aerosol distribution. As a result the
Angström exponent of the aerosol increases. The Angström exponent is
very sensitive for changes in relative humidity during cloud evaporation,
especially between 90% and 100%. In addition, kinetic limitations
delay evaporation of relatively large cloud drops, especially in clean and
mildly polluted environments where the coarse mode fraction is relatively
large. This hampers a direct relation between the aerosol optical thickness,
the Angström exponent and the ambient relative humidity, which may
severely complicate interpretation of these parameters in terms of aerosol
properties, such as the fine mode fraction. |
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