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Dynamic Turbulence Modelling in Large-eddy Simulations of the Cloud-topped Atmospheric Boundary LayerThe use of large eddy simulation, or LES, to study the atmospheric boundary layer dates back to the early 1970s when Deardor (1972) used a three-dimensional simulation to determine velocity and temperature scales in the convective boundary layer. In 1974 he applied LES to the problem of mixing layer entrainment (Deardor 1974) and in 1980 to the cloud-topped boundary layer (Deardor 1980b). Since that time the LES approach has been applied to atmospheric boundary layer problems by numerous authors. While LES has been shown to be relatively robust for simple cases such as a clear, convective boundary layer (Mason 1989), simulation of the cloud-topped boundary layer has proved more of a challenge. The combination of small length scales and anisotropic turbulence coupled with cloud microphysics and radiation effects places a heavy burden on the turbulence model, especially in the cloud-top region. Consequently, over the past few decades considerable effort has been devoted to developing turbulence models that are better able to parameterize these processes. Much of this work has involved taking parameterizations developed for neutral boundary layers and deriving corrections to account for buoyancy effects associated with the background stratification and local buoyancy sources due to radiative and latent heat transfer within the cloud (see Lilly 1962; Deardor 1980a; Mason 1989; MacVean & Mason 1990, for example). In this paper we hope to contribute to this effort by presenting a number of turbulence models in which the model coefficients are calculated dynamically during the simulation rather than being prescribed a priori.
Document ID
20040028003
Acquisition Source
Ames Research Center
Document Type
Other
Authors
Kirkpatrick, M. P. (Stanford Univ. Stanford, CA, United States)
Mansour, N. N. (Stanford Univ. Stanford, CA, United States)
Ackerman, A. S. (NASA Ames Research Center Moffett Field, CA, United States)
Stevens, D. E. (Lawrence Livermore National Lab. Livermore, CA, United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2003
Subject Category
Meteorology And Climatology
Funding Number(s)
CONTRACT_GRANT: NCC2-1371
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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