Comparison of Different Simple Turbulence Closures with a One-Dimensional Boundary Layer Model

Abstract

A comparison of simple turbulence closures with a one-dimensional boundary layer model is presented in order to select one for a three-dimensional nonhydrostatic model applied to the transport-diffusion problem in complex terrain. This study is based on a comparison between measurements and numerical simulations during three experiments: the Wangara experiment; a case of diurnal evolution of a boundary layer in clear sky conditions; and the Cabauw and JASIN (Joint Air?Sea Interaction) experiments concerning the interaction between turbulent and radiative processes in cloud layers (fog and stratocumulus). The results obtained with the e-? equations and with the turbulent kinetic equation using dissipative and mixing lengths are rather similar. The formulation of Louis using a diagnostic diffusion coefficient, slightly modified to take cloud layers into account, gives satisfactory results in view of its simplicity.