Large Eddy Simulation of neutrally stratified and convective planetary boundary layers

A large eddy simulation (LES) technique is gradually becoming a popular tool to investigate turbulent environmental flows. The LES code is based on filtered Navier-Stokes equations, which describe motions of incompressible, Boussinesq fluid at high Reynolds numbers. The code computes directly large-scale, non-universal turbulence in the PBL whereas small-scale, universal turbulence is parameterized by a dynamic mixed subgrid closure. In present work we investigate the structure of neutrally stratified and convective planetary boundary layers. The results of simulation of neutrally stratified planetary boundary layer represent dependencies of boundary layer structure on surface Rossby number: drag coefficient, cross isobaric angle, velocity profiles, momentum fluxes profiles, turbulent kinetic energy, variances of vertical and horizontal velocity components. In the case of convective boundary layer we obtain profile of horizontal velocity components and potential temperature. We also investigate development of convective planetary boundary layer over time. In particular, we obtain dependence of the main characteristics of the turbulence on the thickness of the convective boundary layer and the heat flux on the underlying surface.