Zusammenfassung: | |
A detailed analysis of the pressure-scrambling terms (i.e., the pressure-strain and pressure gradient-scalar covariances) in the Reynolds-stress and scalar-flux budgets for cloud-topped boundary layers (CTBLs) is performed using high-resolution large-eddy simulation (LES). Two CTBLs are simulated — one with trade wind shallow cumuli, and the other with nocturnal marine stratocumuli. The pressure-scrambling terms are decomposed into contributions due to turbulence-turbulence interactions, mean velocity shear, buoyancy, and Coriolis effects. Commonly used models of these contributions, including a simple linear model most often used in geophysical applications and a more sophisticated two-component-limit (TCL) nonlinear model, are tested against the LES data. The decomposition of the pressure-scrambling terms shows that the turbulence-turbulence and buoyancy contributions are most significant for cloud-topped boundary layers. The Coriolis contribution is negligible. The shear contribution is generally of minor importance inside the cloudy layers, but it is the leading-order contribution near the surface. A comparison of models of the pressure-scrambling terms with the LES data suggests that the more complex TCL model is superior to the simple linear model only for a few contributions. The linear model is able to reproduce the principal features of the pressure-scrambling terms reasonably well. It can be applied in the second-order turbulence modeling of cloud-topped boundary layer flows, provided some uncertainties are tolerated.
|
|
Lizenzbestimmungen: | CC BY-NC-ND 4.0 Unported - https://creativecommons.org/licenses/by-nc-nd/4.0/ |
Publikationstyp: | Article |
Publikationsstatus: | publishedVersion |
Erstveröffentlichung: | 2016 |
Schlagwörter (englisch): | cloud-topped boundary layers, large-eddy simulation, parameterizations, pressure-scrambling terms, second-order turbulence modeling, Atmospheric thermodynamics, Boundary layer flow, Boundary layers, Budget control, Buoyancy, Pressure gradient, Reynolds equation, Reynolds number, Shear flow, Turbulence, Uncertainty analysis, Cloud-topped boundary layer, Comparison of models |
Fachliche Zuordnung (DDC): | 550 | Geowissenschaften |
Anzeige der Dokumente mit ähnlichem Titel, Autor, Urheber und Thema.