A simple radiative-convective model with a hydrological cycle and interactive

We have developed a simple, analytically tractable radiative-convective mod el of the tropical climate system that includes an explicit moisture budget , a simple convection parametrization, a simple but physically based radiat ion parametrization, and interactive clouds. The underlying surface is assu med to be ocean. The model includes prognostic equations for the sea surfac e temperature and the vertically integrated water vapour content. A stratos phere in radiative equilibrium limits the depth of the convective layer. Th e lower-tropospheric lapse rate, surface evaporation rate, and clear-sky lo ng-wave and shea-wave radiative fluxes at the surface and the top of the at mosphere are determined as functions of the sea surface temperature and pre cipitable water only. The radiative-convective equilibria of the model atmo sphere resemble the observed tropical climate, if realistic sea surface tem peratures are prescribed. However, cloud-free radiative-convective equilibr ia of the tropical atmosphere-ocean system do not occur for realistic value s of the surface albedo. When cloud radiative effects are included, the mod el produces radiative-convective equilibria that are unrealistically warm. With prescribed realistic lateral energy and moisture transports, however, the equilibria of the model are realistic.