Because GCMs require massive computer resources, other approaches to modelling climate have developed. A variant of the GCM is the statistical-dynamical model (SDM), in which only zonally averaged features are analysed, and north-south energy and momentum exchanges are not treated explicitly but are represented statistically through parameterization. Simpler still are the energy balance model (EBM) and the radiative convective model (RCM). The EBM assumes a global radiation balance and describes the integrated north-south transports of energy in terms of the poleward temperature gradients; EBMs can be one-dimensional (latitude variations only), two-dimensional (latitude-longitude, with simple land-ocean weightings or simplified geography) and even zero-dimensional (averaged for the globe). They are used particularly in climate change studies. The RCMs can represent a single, globally averaged vertical column. The vertical temperature structure is analysed in terms of radiative and convective exchanges. These less complete models complement the GCMs because, for example, the RCM allows study of complex cloud-radiation interactions or the effect of atmospheric composition on lapse rates in the absence of many complicating circulation effects. Simpler models are also important for simulating palaeoclimate as these models can represent thousands or even millions of years of climate history.
Source: From Barry and Carleton (2001).
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