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| Titel |
Simulating Aerosol over Europe with a Limited-Area Regional Climate Model |
| VerfasserIn |
Elias Zubler, Ulrike Lohmann, Daniel Lüthi, Sara Pousse-Nottelmann, Christoph Schär, Martin Wild |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250038526
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| Zusammenfassung |
| Due to their relatively short lifetimes, aerosols are of importance on the regional scale.
Their concentration and composition is different in urban, industrial and agricultural
areas, biomass burning regions, along ship tracks and in arid places. Hence, it is
crucial to use regional climate models (RCMs) which apply sophisticated aerosol
and cloud microphysics schemes in order to cope with the enormous complexity
and the spatial as well as the temporal heterogeneity of the interactions between
aerosols, radiation, clouds and precipitation. Therefore, a new regional modelling
framework is being developed within COSMO-CLM in order to simulate aerosol
dynamics and their effects on clouds, radiation and precipitation at sufficiently high
resolution, also allowing applications on climatological timescales (e.g. the simulation of
decadal European temperature and precipitation trends). COSMO-CLM is coupled to
the aerosol dynamics module M7 and the 2-moment cloud scheme of Seifert &
Beheng (2006). The simulations are driven by ERA-Interim. In addition, the new
model setup requires 3D tracer information at the lateral boundaries from a global
circulation model (GCM). In this study, we therefore evaluate the performance of the
new model setup with respect to aerosol and cloud properties. Furthermore, we
compare the new setup with the standard version of the model not including aerosol
effects.
Over the evaluation period from 1997 to 2003 the new aerosol modelling framework
compares well with the standard version of COSMO-CLM. The monthly and seasonal mean
temperature biases for Greater Europe are similar in terms of spatial distribution
and the annual cycle. The new model version also reproduces the annual cycle
of precipitation, although drier in general than the simulation with the standard
setup.
The model is able to reproduce important cloud and aerosol properties. The effective
cloud droplet radius as well as the cloud radiative forcing are simulated reasonably in
comparison with satellite observations. Aerosol optical depth (AOD) and absorption optical
depth are validated against satellite data, showing an acceptable agreement in the annual
mean despite an underestimation of AOD in winter and a weak overestimation of
the spring peaks related to dust outbreaks from the Saharan desert. Annual mean
aerosol burdens as well as wet and dry deposition rates over Europe show similar
large-scale patterns as nudged simulations with the GCM ECHAM5-HAM. These results
indicate that the new model setup can be considered competitive with previous
model versions in terms of its overall climatological performance, but it allows
to consider interactively coupled direct, semi-direct and indirect aerosol effects. |
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