A physical parameterization package for intermediate tropical atmospheric models is presented. This package includes a linearized longwave radiation scheme, a simplified solar radiation scheme, and a diagnostic cloudiness prediction scheme. The longwave radiation scheme (Chou and Neelin 1996) can reproduce with reasonable accuracy the longwave radiative fluxes associated with tropical interannual variability, seasonal variations, etc. The solar radiation scheme for calculating surface solar irradiance and net atmospheric absorption is simplified from the Fu and Liou (1993) solar radiation scheme. The cloudiness prediction scheme used here diagnostically predicts cloud fraction of deep cloud and cirro-cumulus/cirro-stratus which are the most important cloud types associated with interaction between cumulus convection and large-scale circulation.
A "quasi-equilibrium Tropical circulation model" (Neelin and Zeng 1998) with the physical parameterization package described above is used to examine the impact of radiative feedbacks on simulation of the tropical climatology. The interaction between clouds and radiation is not only a local process but also involves the large-scale circulation. Green house effect feedbacks involve differential effects between relatively clear regions and convection zones and so can impact the spatial form and extent of convection zones. Even in the very simple example of adding constant atmospheric solar absorption, the magnitude and the shape of the intertropical convergence zone can change due to nonlinear effects associated with the circulation between convective regions and clear sky regions. These feedbacks will be analyzed