Improved bora wind simulation using a nested Eta Model

Abstract

This paper reports on improvements obtained in simulations of bora wind using a nesting technique in a primitive equations model. A version of the so-called Eta Model is used for both the lower resolution as well as for the higher resolution nested run. For nesting, a technique has been developed whereby for the boundary conditions “underground” model values are used. They are obtained by horizontal interpolation of model variables inside the model's eta layers. Simulations are initialized using real data. This is done in order to assess the model's performance in simulating the bora wind, an important mesoscale phenomenon caused by orography. Improvements achieved by nesting are illustrated by examples of precipitation as well as a trajectories forecast.