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| Titel |
Cloud albedo increase from carbonaceous aerosol |
| VerfasserIn |
W. R. Leaitch, U. Lohmann, L. M. Russell, T. Garrett, N. C. Shantz, D. Toom-Sauntry, J. W. Strapp, K. L. Hayden, J. Marshall, M. Wolde, D. R. Worsnop, J. T. Jayne |
| 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. 16 ; Nr. 10, no. 16 (2010-08-18), S.7669-7684 |
| Datensatznummer |
250008712
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| Publikation (Nr.) |
 copernicus.org/acp-10-7669-2010.pdf |
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| Zusammenfassung |
| Airborne measurements from two consecutive days, analysed with the aid of an
aerosol-adiabatic cloud parcel model, are used to study the effect of
carbonaceous aerosol particles on the reflectivity of sunlight by water
clouds. The measurements, including aerosol chemistry, aerosol microphysics,
cloud microphysics, cloud gust velocities and cloud light extinction, were
made below, in and above stratocumulus over the northwest Atlantic Ocean. On
the first day, the history of the below-cloud fine particle aerosol was
marine and the fine particle sulphate and organic carbon mass concentrations
measured at cloud base were 2.4 μg m−3 and 0.9 μg m−3
respectively. On the second day, the below-cloud aerosol was continentally
influenced and the fine particle sulphate and organic carbon mass
concentrations were 2.3 μg m−3 and 2.6 μg m−3
respectively. Over the range 0.06–0.8 μm diameter, the shapes of the
below-cloud size distributions were similar on both days and the number
concentrations were approximately a factor of two higher on the second day.
The cloud droplet number concentrations (CDNC) on the second day were
approximately three times higher than the CDNC measured on the first day.
Using the parcel model to separate the influence of the differences in gust
velocities, we estimate from the vertically integrated cloud light
scattering measurements a 6% increase in the cloud albedo principally due
to the increase in the carbonaceous components on the second day. Assuming
no additional absorption by this aerosol, a 6% albedo increase translates
to a local daytime radiative cooling of ∼12 W m−2. This result
provides observational evidence that the role of anthropogenic carbonaceous
components in the cloud albedo effect can be much larger than that of
anthropogenic sulphate, as some global simulations have indicated. |
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