A seasonal global climate model with an equivalent meridional atmospheric circulation

Abstract

A seasonal, zonally averaged, climate model is developed using a hypothetical meridional circulation, which reproduces the atmospheric dynamical heating of a two-level general circulation model. In order to simulate the seasonal temperature cycle, prognostic equations for the land and ocean temperatures are included in the model. The horizontal heat transport in the ocean is modelled as ordinary diffusion. Small-scale vertical transport of sensible and latent heat is described by simple linear terms. For the long-wave radiation calculations, a simple but efficient emissivity approximation scheme is developed. The short-wave radiation treatment is based on an early version of the Mintz-Arakawa general circulation model.

The meridional and seasonal variation of the surface temperature as well as the temperature at the two tropospheric levels are simulated quite well by the model. Concerning surface albedo and planetary albedo, the model gives results which are in good agreement with observed values. Radiative fluxes of the model also compare well with observed values.

The sensitivity of the model to changes in incoming solar radiation and carbon dioxide content is in accordance with results obtained from other models. The model, with variation of the Earth's orbital parameters, has also been used for some preliminary experiments.