Abstract
The turbulent Ekman boundary layer in a neutral atmosphere is studied by means of a second order turbulence closure model incorporated with a prognostic equation for the master length scale and those of a one-and-a-half order closure model. The results of the second order closure model are compared with those of a second order closure model incorporated with an equation for the dissipation rate, an E-ε model and a direct numerical simulation. It is shown that the height of the Ekman layer simulated by the present model is higher than those by the other closure models and that the turbulence kinetic energy and turbulent momentum fluxes in the upper part of the boundary layer are larger. These differences result from the fact that the length scale predicted by the present model is longer than those by the other closure models. The structure of the Ekman boundary layer simulated by the present second order closure model is close to that by a direct numerical simulation. The results of the one-and-a-half order closure model coincide with the present results, though it is found that the growth of the boundary layer is a little slower than that of the present second order closure model.
