Baroclinic Waves and Frontogenesis in a Non-Uniform Potential Vorticity Semi-Geostrophic Model

Abstract

A three-dimensional semi-geostrophic model is used to study the nonlinear development of baroclinic waves on a zonal jet in a model atmosphere with a large change in potential vorticity in the region of the tropopause. The surface frontogenesis proceeds much as in the previous studies in which the tropopause was represented by a lid. However, the upper air development is much more realistic. In particular, there is a locally indirect forcing of the vertical circulation in the region of the upper air front which is easily understood in the present content.