On the Stability of the THIRD-Order Turbulence Closure for the Modeling of the Stratocumulus-Topped Boundary Layer

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  • 1 Centre National de Recherches Météorologiques (DMN/EERM), 31057 Toulouse Cedex, France
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Abstract

It is shown that higher-order turbulence-closure models include as particular solutions damped oscillations in the statically stable case, and possibly amplifying and propagating oscillations in the statically unstable case. These two kinds of oscillatory motions are shown to be strongly affected by molecular and pressure damping, both from analytical linear analysis and one-dimensional numerical simulation. The results are applied to the case of a stratocumulus capped boundary-layer and compared to the ones of Moeng and Randall. Indications are given on how to achieve stable nunneries simulations by improving the formulation of the mixing (dissipative) length.

Abstract

It is shown that higher-order turbulence-closure models include as particular solutions damped oscillations in the statically stable case, and possibly amplifying and propagating oscillations in the statically unstable case. These two kinds of oscillatory motions are shown to be strongly affected by molecular and pressure damping, both from analytical linear analysis and one-dimensional numerical simulation. The results are applied to the case of a stratocumulus capped boundary-layer and compared to the ones of Moeng and Randall. Indications are given on how to achieve stable nunneries simulations by improving the formulation of the mixing (dissipative) length.

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