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| Titel |
Cloud microphysics and aerosol indirect effects in the global climate model ECHAM5-HAM |
| VerfasserIn |
U. Lohmann, P. Stier, C. Hoose, S. Ferrachat, S. Kloster, E. Roeckner, J. Zhang |
| 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 ; 7, no. 13 ; Nr. 7, no. 13 (2007-07-02), S.3425-3446 |
| Datensatznummer |
250005115
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| Publikation (Nr.) |
 copernicus.org/acp-7-3425-2007.pdf |
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| Zusammenfassung |
The double-moment cloud microphysics scheme from ECHAM4 that
predicts both the mass mixing ratios and number concentrations of
cloud droplets and ice crystals has been coupled to the size-resolved aerosol scheme
ECHAM5-HAM. ECHAM5-HAM predicts the aerosol mass, number
concentrations and mixing state. The simulated liquid, ice and total water content
and the cloud droplet and ice crystal number concentrations as a
function of temperature in stratiform mixed-phase clouds between 0 and
−35° C agree much better with aircraft observations in the ECHAM5
simulations. ECHAM5 performs better because more realistic aerosol
concentrations are available for cloud droplet nucleation and because
the Bergeron-Findeisen process is parameterized as being more
efficient.
The total anthropogenic aerosol effect includes the direct,
semi-direct and indirect effects and is defined as the difference in
the top-of-the-atmosphere net radiation between present-day and
pre-industrial times. It amounts to −1.9 W m−2 in ECHAM5, when a
relative humidity dependent cloud cover scheme and aerosol
emissions representative for the years 1750 and 2000 from the AeroCom
emission inventory are used. The contribution
of the cloud albedo effect amounts to −0.7 W m−2.
The total anthropogenic aerosol effect is larger when
either a statistical cloud cover scheme or a different aerosol
emission inventory are employed because the cloud lifetime
effect increases. |
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