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| Titel |
Modeling of Saharan dust outbreaks over the Mediterranean by RegCM3: case studies |
| VerfasserIn |
M. Santese, M. R. Perrone, A. S. Zakey, F. Tomasi, F. Giorgi |
| 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 ; 10, no. 1 ; Nr. 10, no. 1 (2010-01-11), S.133-156 |
| Datensatznummer |
250007897
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| Publikation (Nr.) |
 copernicus.org/acp-10-133-2010.pdf |
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| Zusammenfassung |
| The regional climate model RegCM3 coupled with a radiatively active aerosol
model with online feedback is used to investigate direct and semi-direct
radiative aerosol effects over the Sahara and Europe in a test case of July 2003.
The aerosol model includes dust particles in addition to sulfates,
hydrophobic and hydrophilic black carbon and organic carbon. The role of the
aerosol online feedback on the radiation budget and the direct radiative
forcing (short-wave and long-wave) by dust particles are investigated by
intercomparing results from three experiments: REF, including all
interactive aerosol components, Exp1, not accounting for the aerosol
radiative feedback, and Exp2 not accounting for desert dust particles. The
comparison of results in the REF experiment with satellite observations,
sun/sky radiometer measurements, and lidar profiles at selected Central
Mediterranean sites reveals that the spatio-temporal evolution of the
aerosol optical depth is reasonably well reproduced by the model during the
entire month of July. Results for the dust outbreaks of 17 and 24 July,
averaged over the simulation domain, show that the daily-mean SW direct
radiative forcing by all particles is −24 Wm−2 and −3.4 Wm−2 on
17 July and −25 Wm−2 and −3.5 Wm−2 on 24 July at the surface and
top of the atmosphere, respectively. This is partially offset by the LW
direct radiative forcing, which is 7.6 Wm−2 and 1.9 Wm−2 on 17 July and
8.4 Wm−2 and 1.9 Wm−2 on 24 July at the surface and top
of the atmosphere, respectively. Hence, the daily-mean SW forcing is offset
by the LW forcing of ~30% at the surface and of ~50% at
the ToA. It is also shown that atmospheric dynamics and hence dust
production and advection processes are dependent on the simulation
assumptions and may significantly change within few tens of kilometers. The
comparison of REF and Exp1 shows that the aerosol online feedback on the
radiation budget decreases the domain-average daily-mean value of the 2 m-temperature,
aerosol column burden (CB), and short-wave (SW) atmospheric
forcing by −0.52 °C, 14%, and 0.9%, respectively on 17 July and by
−0.39 °C, 12% and 12%, respectively on 24 July. The comparison of
REF and Exp2 reveals that on 17 July, radiatively-active dust particles
decrease the daily-mean 2 m-temperature averaged over the whole simulation
domain by 0.4% even if are responsible for 99.8% and 97% of the
daily-mean aerosol column burden and SW atmospheric forcing, respectively. |
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