A subgrid parameterization scheme for precipitation
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...
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Copernicus Publications
2012-04-01
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Series: | Geoscientific Model Development |
Online Access: | http://www.geosci-model-dev.net/5/499/2012/gmd-5-499-2012.pdf |
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doaj-6bd887cb35ba497ba95687b4dbb1efde2020-11-24T21:20:01ZengCopernicus PublicationsGeoscientific Model Development1991-959X1991-96032012-04-015249952110.5194/gmd-5-499-2012A subgrid parameterization scheme for precipitationS. TurnerJ.-L. BrenguierC. LacWith 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.http://www.geosci-model-dev.net/5/499/2012/gmd-5-499-2012.pdf |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
S. Turner J.-L. Brenguier C. Lac |
spellingShingle |
S. Turner J.-L. Brenguier C. Lac A subgrid parameterization scheme for precipitation Geoscientific Model Development |
author_facet |
S. Turner J.-L. Brenguier C. Lac |
author_sort |
S. Turner |
title |
A subgrid parameterization scheme for precipitation |
title_short |
A subgrid parameterization scheme for precipitation |
title_full |
A subgrid parameterization scheme for precipitation |
title_fullStr |
A subgrid parameterization scheme for precipitation |
title_full_unstemmed |
A subgrid parameterization scheme for precipitation |
title_sort |
subgrid parameterization scheme for precipitation |
publisher |
Copernicus Publications |
series |
Geoscientific Model Development |
issn |
1991-959X 1991-9603 |
publishDate |
2012-04-01 |
description |
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. |
url |
http://www.geosci-model-dev.net/5/499/2012/gmd-5-499-2012.pdf |
work_keys_str_mv |
AT sturner asubgridparameterizationschemeforprecipitation AT jlbrenguier asubgridparameterizationschemeforprecipitation AT clac asubgridparameterizationschemeforprecipitation AT sturner subgridparameterizationschemeforprecipitation AT jlbrenguier subgridparameterizationschemeforprecipitation AT clac subgridparameterizationschemeforprecipitation |
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