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Simple Parameterization Coupling the Convective Daytime Boundary Layer and Fair-Weather Cumuli. Berg, Larry K.; Stull, Roland B.
Abstract
A new parameterization for boundary layer cumulus clouds, called the cumulus potential (CuP) scheme, is introduced. This scheme uses joint probability density functions (JPDFs) of virtual potential temperature ( ) and water-vapor mixing ratio (r), as well as the mean vertical profiles of , to predict the amount and size distribution of boundary layer cloud cover. This model considers the diversity of air parcels over a heterogeneous surface, and recognizes that some parcels rise above their lifting condensation level to become cumulus, while other parcels might rise as noncloud updrafts. This model has several unique features: 1) cloud cover is determined from the boundary layer JPDF of versus r, 2) clear and cloudy thermals are allowed to coexist at the same altitude, and 3) a range of cloud-base heights, cloud-top heights, and cloud thicknesses are predicted within any one cloud field, as observed. Using data from Boundary Layer Experiment 1996 and a model intercomparsion study using large eddy simulation (LES) based on Barbados Oceanographic and Meteorological Experiment (BOMEX), it is shown that the CuP model does a good job predicting cloud-base height and cloud-top height. The model also shows promise in predicting cloud cover, and is found to give better cloud-cover estimates than three other cumulus parameterizations: one based on relative humidity, a statistical scheme based on the saturation deficit, and a slab model. Copyright 2005 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a web site or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS Copyright Policy, available on the AMS Web site located at (http://www.ametsoc.org/) or from the AMS at 617-227-2425 or copyright@ametsoc.org.
Item Metadata
Title |
Simple Parameterization Coupling the Convective Daytime Boundary Layer and Fair-Weather Cumuli.
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Creator | |
Publisher |
American Meteorological Society
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Date Issued |
2005-06
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Description |
A new parameterization for boundary layer cumulus clouds, called the cumulus potential (CuP) scheme,
is introduced. This scheme uses joint probability density functions (JPDFs) of virtual potential temperature
( ) and water-vapor mixing ratio (r), as well as the mean vertical profiles of , to predict the amount and
size distribution of boundary layer cloud cover. This model considers the diversity of air parcels over a
heterogeneous surface, and recognizes that some parcels rise above their lifting condensation level to
become cumulus, while other parcels might rise as noncloud updrafts. This model has several unique
features: 1) cloud cover is determined from the boundary layer JPDF of versus r, 2) clear and cloudy
thermals are allowed to coexist at the same altitude, and 3) a range of cloud-base heights, cloud-top heights,
and cloud thicknesses are predicted within any one cloud field, as observed.
Using data from Boundary Layer Experiment 1996 and a model intercomparsion study using large eddy
simulation (LES) based on Barbados Oceanographic and Meteorological Experiment (BOMEX), it is
shown that the CuP model does a good job predicting cloud-base height and cloud-top height. The model
also shows promise in predicting cloud cover, and is found to give better cloud-cover estimates than three
other cumulus parameterizations: one based on relative humidity, a statistical scheme based on the saturation
deficit, and a slab model. Copyright 2005 American Meteorological Society (AMS). Permission
to use figures, tables, and brief excerpts from this work in scientific and educational
works is hereby granted provided that the source is acknowledged. Any use of material in
this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act
or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17
USC §108, as revised by P.L. 94-553) does not require the AMS’s permission.
Republication, systematic reproduction, posting in electronic form, such as on a web site
or in a searchable database, or other uses of this material, except as exempted by the
above statement, requires written permission or a license from the AMS. Additional
details are provided in the AMS Copyright Policy, available on the AMS Web site
located at (http://www.ametsoc.org/) or from the AMS at 617-227-2425 or
copyright@ametsoc.org.
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Genre | |
Type | |
Language |
eng
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Date Available |
2011-04-11
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0041850
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URI | |
Affiliation | |
Citation |
Berg, Larry K., Stull, Roland B. 2005. Simple Parameterization Coupling the Convective Daytime Boundary Layer and Fair-Weather Cumuli. Journal of the Atmospheric Sciences. 62(6) 1976-1988.
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Publisher DOI |
10.1175/JAS3437.1
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Peer Review Status |
Reviewed
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Scholarly Level |
Faculty
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Copyright Holder |
Stull, Roland B.
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Rights URI | |
Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International