Atmos. Chem. Phys. Discuss., 11, 20203-20243, 2011
www.atmos-chem-phys-discuss.net/11/20203/2011/
doi:10.5194/acpd-11-20203-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Aerosol-cloud-precipitation effects over Germany as simulated by a convective-scale numerical weather prediction model
A. Seifert1, C. Köhler1,2, and K. D. Beheng3
1Deutscher Wetterdienst, Offenbach, Germany
2Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germany
3Karlsruher Institut für Technologie, Karlsruhe, Germany

Abstract. Possible aerosol-cloud-precipitation effects over Germany are investigated using the COSMO model in a convection-permitting configuration close to the operational COSMO-DE. Aerosol effects on clouds and precipitation are modeled by using an advanced two-moment microphysical parameterization taking into account aerosol assumptions for cloud condensation nuclei (CCN) as well as ice nuclei (IN). Simulations of three summer seasons have been performed with various aerosol assumptions, and are analysed regarding surface precipitation, cloud properties, and the indirect aerosol effect on near-surface temperature. We find that the CCN and IN assumptions have a strong effect on cloud properties, like condensate amounts of cloud water, snow and rain as well as on the glaciation of the clouds, but the effects on surface precipitation are – when averaged over space and time – small. This robustness can only be understood by the combined action of microphysical and dynamical processes. On one hand, this shows that clouds can be interpreted as a buffered system where significant changes to environmental parameters, like aerosols, have little effect on the resulting surface precipitation. On the other hand, this buffering is not active for the radiative effects of clouds, and the changes in cloud properties due to aerosol perturbations have a significant effect on radiation and near-surface temperature.

Citation: Seifert, A., Köhler, C., and Beheng, K. D.: Aerosol-cloud-precipitation effects over Germany as simulated by a convective-scale numerical weather prediction model, Atmos. Chem. Phys. Discuss., 11, 20203-20243, doi:10.5194/acpd-11-20203-2011, 2011.
 
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