Turbulent stratified flows over orography with large scale forcing-concepts and idealised models

Some qualitative features of stratified steady flows over hills , (with height less than the boundary layer depth), and over mountains (with height greater than the boundary layer depth) are still not well described even when the flows are driven by large-scale forcing and have simple Gaussian shapes. The main focus of the present study is on the effects of stratification over the terrain when it is produced by incident large scale flow and when it is also produced by local unsteady heating and cooling in the surface layer. The aim is to extend current quasi-linear idealised models to demonstrate mechanisms and interactions of these various elements in the flow in order to analyse observations and make predictions of the wind field in particular complex terrain environments. We will present this new modeling approach and the mapping of these phenomena into the parameter spaces of shape, size, and stratification.