STABLE NOCTURNAL BOUNDARY-LAYERS - A COMPARISON OF ONE-DIMENSIONAL AND LARGE-EDDY SIMULATION-MODELS

A one-dimensional model and a large-eddy simulation (LES) model are us ed to simulate the turbulence structure of a stably stratified atmosph eric boundary layer. The results are compared with those obtained by A ndren (1995) using a similar three-dimensional model and with experime ntal data. The one-dimensional model solves the fundamental equations of momentum, entropy and conservation of two scalars, and a diagnostic second-order closure model is used to determine the turbulent fluxes of the variables as well as the variances of the velocity and scalars, The two LES models differ in the definition of the sub-grid scale sch eme. The comparison of the model results outlines the differences and the similarities between the three- and the one-dimensional simulation s. Although the results of the two LES models differ in the descriptio n of some of the stable boundary layer turbulence features, it is show n that good agreement is obtained with local-similarity theory and exp erimental data. The differences between the results of three models re late to the stratification within the layer, the asymptotic value of t he various turbulent variables for large stability regimes and their v alues close to the surface.