ABSTRACT

We present a series of dynamical states using an idealized three-dimensional general circulation model with gray radiation and latent heat release. Beginning with the case of radiative-convective equilibrium, we develop a two-dimensional state with zonally symmetric flow followed by a three-dimensional state that includes baroclinic eddy fluxes. In both dry and moist cases, the contribution of eddy fluxes to the general circulation is necessary to reproduce an Earth-like Hadley cell. Additionally, the deepening of the tropical tropospheric layer and the shape of the extratropical tropopause can be understood through the eddy-driven Brewer-Dobson circulation. These results suggest that the standard theory for an axisymmetric Hadley circulation implicitly assumes contributions from baroclinic eddy fluxes and that eddies alone can generate a realistic tropopause structure in the absence of moist convection. We also examine the transport of a tracer from the equatorial stratosphere to the surface as an analogy to downward oxygen transport on early Earth. We discuss how we might extend this tracer to represent various atmospheric constituents and improve upon the physics of our model in order to simulate planets with dense carbon dioxide atmospheres.