A simple parameterization for the turbulent kinetic energy transport terms in the convective boundary layer derived from large eddy simulation |
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Authors: | Franciano Scremin Puhales,Umberto Rizza,Gervá sio Annes Degrazia,Otá vio Costa Acevedo |
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Affiliation: | 1. Departamento de Física, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil;2. Istituto di Scienze dell’Atmosfera e del Clima, Consiglio Nazionale delle Ricerche, Lecce, Italy;3. Instituto Federal Farroupilha, Campus Júlio de Castilhos, RS, Brazil |
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Abstract: | In this work a parametrization for the transport terms of the turbulent kinetic energy (TKE) budget equation, valid for a convective boundary layer (CBL) is presented. This is a hard task to accomplish from experimental data, especially because of the difficulty associated to the measurements of pressure turbulent fluctuations, which are necessary to determine the pressure correlation TKE transport term. Thus, employing a large eddy simulation (LES) a full diurnal planetary boundary layer (PBL) cycle was simulated. In this simulation a forcing obtained from experimental data is used, so that the numerical experiment represents a more realistic case than a stationary PBL. For this study all terms of the TKE budget equation were determined for a CBL. From these data, polynomials that describe the TKE transport terms’ vertical profiles were adjusted. The polynomials found are a good description of the LES data, and from them it is shown that a simple formulation that directly relates the transport terms to the TKE magnitude has advantages on other parameterizations commonly used in CBL numerical models. Furthermore, the present study shows that the TKE turbulent transport term dominates over the TKE transport by pressure perturbations and that for most of the CBL these two terms have opposite signs. |
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Keywords: | LES Turbulence Atmospheric boundary layer TKE budget |
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