Large Eddy Simulations of the Atmospheric Flow in Alpine Environments

Land atmosphere interaction within an alpine catchment is a driving force behind the physical processes of latent heat transport, and evaporative transport. Such physical processes are crucial elements in the analysis and understanding of the energy and water balances within a catchment. In this work, Large Eddy Simulations (LES) of an alpine region that includes the Gaudergrat ridge are performed and analyzed. First, the LES code, using the immersed boundary method, is validated against wind tunnel data of flow over a steep three dimensional Gaussian hill. Here, comparisons are favorable in both flow velocity and variance profiles. The validated LES code is then used to perform high resolution simulations of the atmospheric flow over an alpine area located in eastern Switzerland. These simulation results are further compared against lower resolution mesoscale models of the same region as well as in-situ measurements from the intensive GAUDEX 2003 measurement campaign.