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Title: Parameterizing deep convection using the assumed probability density function method

Due to their coarse horizontal resolution, present-day climate models must parameterize deep convection. This paper presents single-column simulations of deep convection using a probability density function (PDF) parameterization. The PDF parameterization predicts the PDF of subgrid variability of turbulence, clouds, and hydrometeors. That variability is interfaced to a prognostic microphysics scheme using a Monte Carlo sampling method. The PDF parameterization is used to simulate tropical deep convection, the transition from shallow to deep convection over land, and mid-latitude deep convection. These parameterized single-column simulations are compared with 3-D reference simulations. The agreement is satisfactory except when the convective forcing is weak. The same PDF parameterization is also used to simulate shallow cumulus and stratocumulus layers. The PDF method is sufficiently general to adequately simulate these five deep, shallow, and stratiform cloud cases with a single equation set. This raises hopes that it may be possible in the future, with further refinements at coarse time step and grid spacing, to parameterize all cloud types in a large-scale model in a unified way.
Authors:
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Publication Date:
OSTI Identifier:
1227767
Grant/Contract Number:
SC0008668; SC0008323
Type:
Published Article
Journal Name:
Geoscientific Model Development Discussions (Online)
Additional Journal Information:
Journal Name: Geoscientific Model Development Discussions (Online); Journal Volume: 7; Journal Issue: 3; Journal ID: ISSN 1991-962X
Publisher:
European Geosciences Union
Sponsoring Org:
USDOE
Country of Publication:
Germany
Language:
English