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| Titel |
A subgrid parameterization scheme for precipitation |
| VerfasserIn |
S. Turner, J.-L. Brenguier, C. Lac |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 5, no. 2 ; Nr. 5, no. 2 (2012-04-23), S.499-521 |
| Datensatznummer |
250002454
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| Publikation (Nr.) |
 copernicus.org/gmd-5-499-2012.pdf |
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| Zusammenfassung |
| With increasing computing power, the horizontal resolution of numerical
weather prediction (NWP) models is improving and today reaches 1 to 5 km.
Nevertheless, clouds and precipitation formation are still subgrid scale
processes for most cloud types, such as cumulus and stratocumulus. Subgrid
scale parameterizations for water vapor condensation have been in use for
many years and are based on a prescribed probability density function (PDF)
of relative humidity spatial variability within the model grid box, thus
providing a diagnosis of the cloud fraction. A similar scheme is developed
and tested here. It is based on a prescribed PDF of cloud water variability
and a threshold value of liquid water content for droplet collection to
derive a rain fraction within the model grid. Precipitation of rainwater
raises additional concerns relative to the overlap of cloud and rain
fractions, however. The scheme is developed following an analysis of data
collected during field campaigns in stratocumulus (DYCOMS-II) and fair
weather cumulus (RICO) and tested in a 1-D framework against large eddy
simulations of these observed cases. The new parameterization is then
implemented in a 3-D NWP model with a horizontal resolution of 2.5 km to
simulate real cases of precipitating cloud systems over France. |
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