The Tropopause in a 2D Circulation Model

Abstract

The influence of baroclinic waves on tropopause height was studied with a 2D version of the standard climate 3D GCM ECHAM3. The main feature of the 2D version is a self-consistent parameterization of the transient tropospheric eddy heat and momentum fluxes. The mixing processes that result from the stratospheric planetary waves are prescribed according to climatological data. The model calculations were made with and without the parameterized eddy fluxes, separately revealing the effect of midlatitude tropopause lifting due to the tropospheric eddies and the effect of midlatitude tropopause steepening due to the stratospheric circulation. These effects are also demonstrated by the temperature and the lapse rate of the model results and, additionally, by the meridional distribution of trace gas constituents when the 2D model is run as a dynamical?chemical transport model. The results reveal the strong dependence of the tropopause height on the strength of the stratospheric circulation.