Energy balance climate modeling: Comparison of radiative and dynamic feedback mechanisms

The time dependent energy balance climate model of Schneider and Gal-Chen (1973) is extended to consider the relative importance of radiative and dynamic parameterizations on the sensitivity of the model's equilibrium climate to perturbations in solar input. The albedo-temperature feedback parameterization of Sellers (1969) is used to test the sensitivity of the model's global temperature and equator-to-pole temperature gradient to solar input changes with six different dynamical parameterizations. The nonlinear eddy flux parameterization used by Stone (1973) appears to give the best results, but the assumption that global average static stability remains constant during climatic changes (on earth) is not supported by our experiments; but also cannot be ruled out as a possibility. The thermodynamic processes of ice-albedo-temperature feedback and moist adiabatic convective adjustment are found to dominate the effects of large-scale eddies in controlling the behavior of the globally-averaged lapse rate during climatic changes. This conclusion is drawn after comparisons of our results with those computed by Wetherald and Manabe with a three-dimensional general circulation model. Our findings suggest that thermodynamic processes must be central elements of any climatic theory, and that interpretation of the results of complex general circulation models can be made easier by drawing on the experience gained with simpler models like the energy balance varieties used here.