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| Titel |
Manipulating marine stratocumulus cloud amount and albedo: a process-modelling study of aerosol-cloud-precipitation interactions in response to injection of cloud condensation nuclei |
| VerfasserIn |
H. Wang, P. J. Rasch, G. Feingold |
| 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. 9 ; Nr. 11, no. 9 (2011-05-06), S.4237-4249 |
| Datensatznummer |
250009701
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| Publikation (Nr.) |
 copernicus.org/acp-11-4237-2011.pdf |
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| Zusammenfassung |
| We use a cloud-system-resolving model to study marine-cloud brightening. We
examine how injected aerosol particles that act as cloud condensation nuclei
(CCN) are transported within the marine boundary layer and how the
additional particles in clouds impact cloud microphysical processes, and
feedback on dynamics. Results show that the effectiveness of cloud
brightening depends strongly on meteorological and background aerosol
conditions. Cloud albedo enhancement is very effective in a weakly
precipitating boundary layer and in CCN-limited conditions preceded by heavy
and/or persistent precipitation. The additional CCN help sustain cloud water
by weakening the precipitation substantially in the former case and
preventing the boundary layer from collapse in the latter. For a given
amount of injected CCN, the injection method (i.e., number and distribution
of sprayers) is critical to the spatial distribution of these CCN. Both the
areal coverage and the number concentration of injected particles are key
players but neither one always emerges as more important than the other. The
same amount of injected material is much less effective in either strongly
precipitating clouds or polluted clouds, and it is ineffective in a
relatively dry boundary layer that supports clouds of low liquid water path.
In the polluted case and "dry" case, the CCN injection increases drop
number concentration but lowers supersaturation and liquid water path. As a
result, the cloud experiences very weak albedo enhancement, regardless of
the injection method. |
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