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Toward a Unified Parameterization of the Boundary Layer and Moist ConvectionA model that employs a new form of mass-flux closure (described in Part I of this paper) is applied to a variety of clear and cloudy planetary boundary layers (PBLs) including dry convection from the Wangara Experiment, trade wind cumulus from the Barbados Oceanographic and Meteorological Experiment (BOMEX), and marine stratocumulus from the Atlantic Stratocumulus Experiment (ASTEX). For Wangara, the simulated variances and fluxes match that expected from similarity arguments, while the mean state is a little less mixed than the observations. In the BOMEX simulation. the shape and magnitude of the fluxes and the turbulence kinetic energy budget agree with LES results and observations. However, the liquid water mixing ratio is too large. This is attributed to an underprediction of the skewness. In agreement with observations from the ASTEX experiment, many of the model-simulated fields distinctly reflect a regime in transition between the trade wind cumulus and the classic stratocumulus-topped boundary layers. In general, the simulated entrainment rate tends to be a little underpredicted in regimes where there is little cloud-top radiative cooling (Wangara and BOMEX), while it is overpredicted in regimes where this process is more critical (e.g., ASTEX). Prior work suggests that this may be related to the manner in which the pressure terms are parameterized in the model. Overall, the model is able to capture some key physical features of these PBL regimes, and appears to have the potential to represent both cloud and boundary layer processes. Thus, this approach is a first step toward unifying these processes in large-scale models.
Document ID
20010082953
Acquisition Source
Langley Research Center
Document Type
Reprint (Version printed in journal)
Authors
Lappen, Cara-Lyn
(Colorado State Univ. Fort Collins, CO United States)
Randall, David A.
(Colorado State Univ. Fort Collins, CO United States)
Date Acquired
August 20, 2013
Publication Date
January 1, 2001
Publication Information
Publication: Journal of the Atmospheric Sciences
Volume: 58
Subject Category
Meteorology And Climatology
Funding Number(s)
CONTRACT_GRANT: NSF OPP-95-04246
CONTRACT_GRANT: JPL-960700
CONTRACT_GRANT: NAG1-1701
Distribution Limits
Public
Copyright
Other

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