A one-dimensional simulation of the stratocumulus-capped mixed layer

Abstract

A marine stratocumulus model has been developed which has four major sub-models: (1) a one-dimensional version of the CSU cumulus model, (2) a partially-diagnostic higher-order turbulence model, (3) an atmospheric radiation model for both short-wave and long-wave radiation, and (4) a partial condensation scheme and cloud fractional parameterization.A set of numerical experiments have been performed to study the interactions among the turbulence, the long-wave radiation, the short-wave radiation, and the sub-grid condensation processes. The results indicate that surface sensible eddy heat flux and not radiative cooling is the major control on the rate of cloud-top entrainment. Cloud-top radiation cooling occurs principally within the upper part of the mixed layer. However, for the stratocumulus with numerous towers penetrated into the capping inversion, most of the long-wave radiation occurs within the capping inversion. It is found that cloud-top radiation cooling is balanced by turbulence transport of sensible heat from cloud-base levels.

Outlook for Research on Subtropical Marine Stratification Clouds

“…Deardorff (1980b) presented results from a highresolution three-dimensional numerical model, which indicate that the onset of the instability is accompanied by rapid entrainment, a significant reduction in cloudiness, and a decrease in the effectiveness of turbulent mixing in maintaining well-mixed in-cloud conditions. Moeng and Arakawa (1980) and Chen and Cotton (1983) obtained similar results using higher-order-closure models. However, Fravalo etal.…”

“…Numerical simulations of stratus and stratocumulus systems have been performed with simple mixed-layer models (Lilly, 1968), higher-order closure models (Moeng and Arakawa, 1980;Chen and Cotton, 1983), large-eddy models (Deardorff, 1980a;Sommeria, 1976), and general circulation models (Suarez et al, 1983;Randall, 1983). As a result of these studies, several key theoretical issues have emerged, and a carefully designed observational program is needed to resolve them.…”

Real-time weather forecasting in the Western Mediterranean Basin: An application of the RAMS model

“…In the present study, the Mellor and Yamada (1982) level 2.5 turbulence parameterization is used. Besides, a full-column two-stream single-band radiation scheme that accounts for clouds to calculate shortwave and long-wave radiation (Chen and Cotton, 1983), and the cloud and precipitation microphysics scheme from Walko et al (1995) is applied in all the domains. The Kuo- (Molinari, 1985), whereas grids 2 and 3 utilizes explicit convection only.…”

Atmospheric Prognostic and Dispersion Model Design for Use in the European ENSEMBLE Modeling Exercises

“…Finally, participation in the ENSEMBLE program has provided SRTC scientists the opportunity to network with many European scientists, and to learn more about the modeling program of these different agencies. Chen and Cotton (1983); f = 1800 s Convective Parameterization Modified Kuo cumulus (Tremback 1990); f = 1800 s Turbulence Parameterization Modified Mellor-Yamada 2.5 (Helfand and Labraga 1988) …”