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| Titel |
Climatology of stratocumulus cloud morphologies: microphysical properties and radiative effects |
| VerfasserIn |
A. Muhlbauer, I. L. McCoy, R. Wood |
| 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. 13 ; Nr. 14, no. 13 (2014-07-03), S.6695-6716 |
| Datensatznummer |
250118857
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| Publikation (Nr.) |
 copernicus.org/acp-14-6695-2014.pdf |
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| Zusammenfassung |
An artificial neural network cloud classification scheme is combined with
A-train observations to characterize the physical properties and radiative
effects of marine low clouds based on their morphology and type of mesoscale
cellular convection (MCC) on a global scale. The cloud morphological
categories are (i) organized closed MCC, (ii) organized open MCC and (iii)
cellular but disorganized MCC.
Global distributions of the frequency of occurrence of MCC types show clear
regional signatures. Organized closed and open MCCs are most frequently found
in subtropical regions and in midlatitude storm tracks of both hemispheres.
Cellular but disorganized MCC are the predominant type of marine low clouds
in regions with warmer sea surface temperature such as in the tropics and
trade wind zones. All MCC types exhibit a pronounced seasonal cycle.
The physical properties of MCCs such as cloud fraction, radar reflectivity,
drizzle rates and cloud top heights as well as the radiative effects of MCCs
are found highly variable and a function of the type of MCC. On a global
scale, the cloud fraction is largest for closed MCC with mean cloud fractions
of about 90%, whereas cloud fractions of open and cellular but disorganized
MCC are only about 51% and 40%, respectively. Probability density functions
(PDFs) of cloud fractions are heavily skewed and exhibit modest regional
variability.
PDFs of column maximum radar reflectivities and inferred cloud base drizzle
rates indicate fundamental differences in the cloud and precipitation
characteristics of different MCC types. Similarly, the radiative effects of
MCCs differ substantially from each other in terms of shortwave reflectance
and transmissivity. These differences highlight the importance of low-cloud
morphologies and their associated cloudiness on the shortwave cloud forcing. |
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