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| Titel |
Aerosol forcing based on CAM5 and AM3 meteorological fields |
| VerfasserIn |
C. Zhou, J. E. Penner, Y. Ming, X. L. Huang |
| 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 ; 12, no. 20 ; Nr. 12, no. 20 (2012-10-24), S.9629-9652 |
| Datensatznummer |
250011526
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| Publikation (Nr.) |
 copernicus.org/acp-12-9629-2012.pdf |
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| Zusammenfassung |
We use a single aerosol model to explore the effects of the differing
meteorological fields from the NCAR CAM5 and GFDL AM3 models. We simulate
the global distributions of sulfate, black carbon, organic matter, dust and
sea salt using the University of Michigan IMPACT model and use these fields
to calculate aerosol direct and indirect forcing, thereby isolating the
impacts of the differing meteorological fields.
Over all, the IMPACT-AM3 model predicts larger burdens and longer aerosol
lifetimes than the IMPACT-CAM5 model. However, the IMPACT-CAM5 simulations
transport more black carbon to the polar regions and more dust from Asia
towards North America. These differences can mainly be attributed to
differences in: (1) the vertical cloud mass flux and large-scale
precipitation fields which determine the wet deposition of aerosols; (2) the
in-cloud liquid water content and the cloud coverage which determine the wet
aqueous phase production of sulfate. The burden, lifetime and global
distribution, especially black carbon in polar regions, are strongly
affected by choice of the parameters used for wet deposition.
The total annual mean aerosol optical depth (AOD) at 550 nm ranges from
0.087 to 0.122 for the IMPACT-AM3 model and from 0.138 to 0.186 for the
IMPACT-CAM5 model (range is due to different parameters used for wet
deposition). Even though IMPACT-CAM5 has smaller aerosol burdens, its AOD is
larger due to the much higher relative humidity in CAM5 which leads to more
hygroscopic growth. The corresponding global annual average anthropogenic and
all-sky aerosol direct forcing at the top of the atmosphere ranges from
−0.25 W m−2 to −0.30 W m−2 for IMPACT-AM3 and from
−0.48 W m−2 to −0.64 W m−2 for IMPACT-CAM5. The global
annual average anthropogenic 1st aerosol indirect effect at the top of the
atmosphere ranges from −1.26 W m−2 to −1.44 W m−2 for
IMPACT-AM3 and from −1.74 W m−2 to −1.77 W m−2 for
IMPACT-CAM5. |
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