Wave Drag and Form Drag Induced by Small Scale Terrain in the Nocturnal Stable Boundary Layer

By solving the linearized atmospheric dynamic equation system including turbulent dissipation, the analytical solutions of wave drag and form drag over small scale terrain in a nocturnal stable boundary layer are obtained. The solutions show that the atmospheric conditions and terrain features such as the stability, wind speed and turbulent dissipation in the stable layer, the depth of the stable layer, the stability and wind speed in the upper residue layer as well as the height and slope of the terrain are all the factors affecting the values of the wave drag and form drag. Those factors should be considered in the parameterization schemes of the wave drag and form drag in a numerical model. The analyses also show that the form drag may be omitted as long as the terrain slope is small to a certain degree.