Project WIND Numerical Simulations with FITNAH

Abstract

The numerical simulation model FITNAH (flow over irregular terrain with natural and anthropogenic heat sources) is used in the present study. It was developed at the Department of Meteorology, Technical University of Darmstadt, for studies of phenomena belonging to the mesoscale γ. Here, the significant horizontal and vertical scales of the flow are of the same order of magnitude; therefore, the hydrostatic assumption is not valid. Since the nonhydrostatic model FIT-NAH is described in detail by Gross (1990), only the basic characteristics are repeated here. The framework of the model consists of the equation of motion with Boussinesq approximation, the continuity equation in the anelastic form, the first law of thermodynamics, and an equation for the conservation of water vapor. This is a set of six equations for the three velocity components (west-east component u south-north component v, vertical component w), potential temperature θ pressure p and specific humidity s.