AN EXAMINATION OF ENERGY BALANCE THEORY USING A THREE-DIMENSIONAL GLOBAL CLIMATE MODEL

摘要

A type of numerical climate model, termed an energy balance model, has been severely criticized for failure to adhere to accepted physical principles, particularly mass-momentum conservation. This study incorporates the balance equation between streamfunction and geopotential into an energy balance model to insure explicit conservation of mass and momentum.;The primary finding of this work is that the variables derived from energy balance theory can be calculated in a numerical climate model incorporating a circulation system that conserves mass and momentum. This represents the first time that an energy balance model explicitly contains a derived circulation and yet does not violate the basic physical principle of mass-momentum conservation. Several other important results are explicit in this finding. Firstly, recognizable features of the observed seasonal circulation are produced using the balance equation in tandem with an energy balance model. The normal intense Rossby wave pattern in the Northern Hemisphere breaks down and weakens as the model progresses from January to July. Secondly, the simulations by this model of our present climate reasonably reproduce many of the observed distributions of major climatic variables such as temperature, evaporation, precipitation and albedo. This model's simulations also compare favorably to early versions of a more complex class of models known as general circulation models. This model is one of the first EBMs to calculate precipitation rates and incorporate those values with temperature in feedback mechanisms involving snow and ice cover.;Finally, this study has shown that a three-dimensional energy balance model with a derived circulation produces features of our climate which are generally comparable to results of accepted general circulation models. When the relative computer efficiency of this model as compared to GCMs is also taken into account, these findings have important implications to climate modelers with limited access or experience with supercomputers.