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| Titel |
Atmospheric black carbon and warming effects influenced by the source and absorption enhancement in central Europe |
| VerfasserIn |
S. Nordmann, Y. F. Cheng, G. R. Carmichael, M. Yu, H. A. C. Denier van der Gon, Q. Zhang, P. E. Saide, U. Pöschl, H. Su, W. Birmili, A. Wiedensohler |
| 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 ; 14, no. 23 ; Nr. 14, no. 23 (2014-12-02), S.12683-12699 |
| Datensatznummer |
250119203
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| Publikation (Nr.) |
 copernicus.org/acp-14-12683-2014.pdf |
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| Zusammenfassung |
| Particles containing black carbon (BC), a strong absorbing substance, exert a
rather uncertain direct and indirect radiative forcing in the atmosphere. To
investigate the mass concentration and absorption properties of BC particles
over central Europe, the model WRF-Chem was used at a resolution of 12 km in
conjunction with a high-resolution BC emission inventory (EUCAARI
42-Pan-European Carbonaceous Aerosol Inventory; 1/8° × 1/16°). The
model simulation was evaluated using measurements of equivalent soot carbon,
absorption coefficients and particle number concentrations at seven sites within
the German Ultrafine Aerosol Network, PM mass concentrations from
the dense measurement network of the German Federal Environmental Agency at
392 monitoring stations, and aerosol optical depth from MODIS and AERONET. A
distinct time period (25 March to 10 April 2009) was chosen, during which the
clean marine air mass prevailed in the first week and afterwards the polluted
continental air mass mainly from the southeast dominated with elevated daily
average BC concentration of up to 4 μ g m−3. The simulated
PM mass concentration, aerosol number concentration and optical
depth were in good agreement with the observations, while the modelled BC
mass concentrations were found to be a factor of 2 lower than the
observations. Together with back trajectories, detailed model bias analyses
suggested that the current BC emission in countries to the east and south of
Germany might be underestimated by a factor of 5, at least for the simulation
period. Running the model with upscaled BC emissions in these regions led to
a smaller model bias and a better correlation between model and measurement.
In contrast, the particle absorption coefficient was positively biased by
about 20% even when the BC mass concentration was underestimated by around
50%. This indicates that the internal mixture treatment of BC in the
WRF-Chem optical calculation is unrealistic in our case, which overamplifies
the light absorption by BC-containing particles. By adjusting the modelled
mass absorption cross-section towards the measured values, the simulation of
particle light absorption of BC was improved as well. Finally, the positive
direct radiative forcing of BC particles at the top of the atmosphere was
estimated to be in the range of 0 to +4 W m−2 over Germany for
the model run with improved BC mass concentration and adjusted BC light
absorption cross-section. This adjustment lowered the positive forcing of BC
by up to 70%, compared with the internal mixing treatment of BC in the model
simulation. |
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