Title: A Large Eddy Simulation Model for the Stratus-Topped Boundary Layer
Abstract: Because of the important impact of the stratus cloud regime on global climate, I have incorporated radiation and condensation processes into my large-eddy-simulation model to simulate the stratus-topped boundary layer. Such simulation helps to understand the turbulent structure within this type of planetary boundary layer (PBL), and. can be used to test the statistical turbulence models which are used as PBL parameterizations in climate models. A sample study for mixed-layer modeling shows that within the stratus-topped mixed layer about 60% of the total buoyant-generated kinetic energy is used for dissipation and the rest converts back to potential energy through thermally indirect motions. I also study the pressure term in the scalar flux equation for second-order closure modeling. Decomposing the pressure fluctuations into different components according to their physical processes allows one to study each component separately. The result shows that in the scalar flux equation the buoyancy component of the pressure term is proportional to the direct buoyant production term; the proportionality constant is about 0.75 for the stratus-topped PBL. The nonlinear interaction component of the pressure term can be represented by Rotta’s return-to-isotropy model, with a time scale profile proportional to (math), where (math) is the vertical velocity variance and € is the kinetic energy dissipation rate.
Publication Year: 1986
Publication Date: 1986-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
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