The Spontaneous Formation of a Tropopause Inversion Layer in Simple, Dry, Atmospheric General Circulation Models

Integrating the Held & Suarez (1994) system with a sufficient number of vertical levels, we show that the recently discovered Tropopause Inversion Layer (Birner, 2006) emerges naturally from the dry dynamics of the flow, in the absence of radiative, convective and moist processes. This result is validated, by computing solutions at different vertical and horizontal resolutions, and by using forcings other that those specified by Held & Suarez, e.g. those in Schneider (2006). In addition, our simple models are able to capture the qualitative latitudinal structure and the seasonal variability in the observations, regardless of the specific details of the equilibrium temperature profiles and model resolutions. Our models, however, only capture half the amplitude (roughly) of the observed inversion layer, suggesting that dynamics alone, while important, is insufficient to fully account for the TIL and that radiative-convective process might be responsible for the larger observed amplitudes.