Structure and Development of Mesoscale Baroclinic Waves in a Nonhydrostatic Numerical Model

Abstract

The structure and development of idealized short mesoscale baroclinic waves are investigated within the framework of several numerical simulations. The numerical model used in this study is a mesoscale version of Clark's nonhydrostatic cloud model generalized to allow horizontally varying basic states. It is shown that short mesoscale disturbances can grow quickly when superimposed on a narrow and intense baroclinic zone having strong potential vorticity anomalies. Simulations with a weaker baroclinic zone yield a significantly weaker development. Results from dry runs with different wavelengths have shown that a natural scale-selection mechanism exists in the numerical model for a given basic state. For the initial data considered in this work, we found a maximum development for a disturbance wavelength of 1200 km.