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| Titel |
Dust vertical profile impact on global radiative forcing estimation using a coupled chemical-transport–radiative-transfer model |
| VerfasserIn |
L. Zhang, Q. B. Li, Y. Gu, K. N. Liou, B. Meland |
| 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 ; 13, no. 14 ; Nr. 13, no. 14 (2013-07-29), S.7097-7114 |
| Datensatznummer |
250018782
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| Publikation (Nr.) |
 copernicus.org/acp-13-7097-2013.pdf |
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| Zusammenfassung |
| Atmospheric mineral dust particles exert significant direct radiative
forcings and are important drivers of climate and climate change. We used
the GEOS-Chem global three-dimensional chemical transport model (CTM)
coupled with the Fu-Liou-Gu (FLG) radiative transfer model (RTM) to
investigate the dust radiative forcing and heating rate based on different
vertical profiles for April 2006. We attempt to actually quantify the
sensitivities of radiative forcing to dust vertical profiles, especially the
discrepancies between using realistic and climatological vertical profiles.
In these calculations, dust emissions were constrained by observations of
aerosol optical depth (AOD). The coupled calculations utilizing a more
realistic dust vertical profile simulated by GEOS-Chem minimize the physical
inconsistencies between 3-D CTM aerosol fields and the RTM. The use of
GEOS-Chem simulated vertical profile of dust extinction, as opposed to the
FLG prescribed vertical profile, leads to greater and more spatially
heterogeneous changes in the estimated radiative forcing and heating rate
produced by dust. Both changes can be attributed to a different vertical
structure between dust and non-dust source regions. Values of the dust
vertically resolved AOD per grid level (VRAOD) are much larger in the middle
troposphere, though smaller at the surface when the GEOS-Chem simulated
vertical profile is used, which leads to a much stronger heating rate in the
middle troposphere. Compared to the FLG vertical profile, the use of
GEOS-Chem vertical profile reduces the solar radiative forcing at the top of
atmosphere (TOA) by approximately 0.2–0.25 W m−2 over the African and
Asian dust source regions. While the Infrared (IR) radiative forcing
decreases 0.2 W m−2 over African dust belt, it increases 0.06 W m−2
over the Asian dust belt when the GEOS-Chem vertical profile is used.
Differences in the solar radiative forcing at the surface between the use of
the GEOS-Chem and FLG vertical profiles are most significant over the Gobi
desert with a value of about 1.1 W m−2. The radiative forcing effect of
dust particles is more pronounced at the surface over the Sahara and Gobi
deserts by using FLG vertical profile, while it is less significant over the
downwind area of Eastern Asia. |
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