Parameterizing microphysical effects on variances and covariances of moisture and heat content using a multivariate probability density function: a study with CLUBB (tag MVCS)
Microphysical processes, such as the formation, growth, and evaporation of precipitation, interact with variability and covariances (e.g., fluxes) in moisture and heat content. For instance, evaporation of rain may produce cold pools, which in turn may trigger fresh convection and precipitation. These effects are usually omitted or else crudely parameterized at subgrid scales in weather and climate models.A more formal approach is pursued here, based on predictive, horizontally averaged equations for the variances, covariances, and fluxes of moisture and heat content. These higherorder moment equations contain microphysical source terms. The microphysics terms can be integrated analytically, given a suitably simple warmrain microphysics scheme and an approximate assumption about the multivariate distribution of cloudrelated and precipitationrelated variables. Performing the integrations provides exact expressions within an idealized context.A largeeddy simulation (LES) of a shallow precipitating cumulus case is performed here, and it indicates that the microphysical effects on (co)variances and fluxes can be large. In some budgets and altitude ranges, they are dominant terms. The analytic expressions for the integrals are implemented in a singlecolumn, higherorder closure model. Interactive singlecolumn simulations agree qualitatively with the LES. The analytic integrations form a parameterization of microphysical effects in their own right, and they alsomore »
 Authors:

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 Univ. of Wisconsin, Milwaukee, WI (United States). Dept. of Mathematical Sciences
 Publication Date:
 Grant/Contract Number:
 SC0008323; AGS0968640
 Type:
 Published Article
 Journal Name:
 Geoscientific Model Development (Online)
 Additional Journal Information:
 Journal Name: Geoscientific Model Development (Online); Journal Volume: 9; Journal Issue: 11; Journal ID: ISSN 19919603
 Publisher:
 European Geosciences Union
 Research Org:
 Univ. of Wisconsin, Milwaukee, WI (United States)
 Sponsoring Org:
 USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC23); National Science Foundation (NSF)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 54 ENVIRONMENTAL SCIENCES
 OSTI Identifier:
 1333515
 Alternate Identifier(s):
 OSTI ID: 1426175
Griffin, Brian M., and Larson, Vincent E.. Parameterizing microphysical effects on variances and covariances of moisture and heat content using a multivariate probability density function: a study with CLUBB (tag MVCS). United States: N. p.,
Web. doi:10.5194/gmd942732016.
Griffin, Brian M., & Larson, Vincent E.. Parameterizing microphysical effects on variances and covariances of moisture and heat content using a multivariate probability density function: a study with CLUBB (tag MVCS). United States. doi:10.5194/gmd942732016.
Griffin, Brian M., and Larson, Vincent E.. 2016.
"Parameterizing microphysical effects on variances and covariances of moisture and heat content using a multivariate probability density function: a study with CLUBB (tag MVCS)". United States.
doi:10.5194/gmd942732016.
@article{osti_1333515,
title = {Parameterizing microphysical effects on variances and covariances of moisture and heat content using a multivariate probability density function: a study with CLUBB (tag MVCS)},
author = {Griffin, Brian M. and Larson, Vincent E.},
abstractNote = {Microphysical processes, such as the formation, growth, and evaporation of precipitation, interact with variability and covariances (e.g., fluxes) in moisture and heat content. For instance, evaporation of rain may produce cold pools, which in turn may trigger fresh convection and precipitation. These effects are usually omitted or else crudely parameterized at subgrid scales in weather and climate models.A more formal approach is pursued here, based on predictive, horizontally averaged equations for the variances, covariances, and fluxes of moisture and heat content. These higherorder moment equations contain microphysical source terms. The microphysics terms can be integrated analytically, given a suitably simple warmrain microphysics scheme and an approximate assumption about the multivariate distribution of cloudrelated and precipitationrelated variables. Performing the integrations provides exact expressions within an idealized context.A largeeddy simulation (LES) of a shallow precipitating cumulus case is performed here, and it indicates that the microphysical effects on (co)variances and fluxes can be large. In some budgets and altitude ranges, they are dominant terms. The analytic expressions for the integrals are implemented in a singlecolumn, higherorder closure model. Interactive singlecolumn simulations agree qualitatively with the LES. The analytic integrations form a parameterization of microphysical effects in their own right, and they also serve as benchmark solutions that can be compared to nonanalytic integration methods.},
doi = {10.5194/gmd942732016},
journal = {Geoscientific Model Development (Online)},
number = 11,
volume = 9,
place = {United States},
year = {2016},
month = {11}
}