Analysis of pressure-strain and pressure gradient-scalar covariances in cloud-topped boundary layers

A large-eddy simulation study

verfasst von

Rieke Heinze, Dmitrii Mironov, Siegfried Raasch

Abstract

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.

Organisationseinheit(en)

Institut für Meteorologie und Klimatologie

Externe Organisation(en)

Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. (MPG)
Deutscher Wetterdienst (DWD)

Typ

Artikel

Journal

Journal of Advances in Modeling Earth Systems

Band

8

Seiten

3-30

Anzahl der Seiten

28

ISSN

1942-2466

Publikationsdatum

22.04.2016

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Globaler Wandel, Umweltchemie, Allgemeine Erdkunde und Planetologie

Ziele für nachhaltige Entwicklung

SDG 14 – Lebensraum Wasser

Elektronische Version(en)

https://doi.org/10.1002/2015MS000508 (Zugang: Offen)