Global Circulation Models (GCM):

General Circulation Models of the Atmosphere (GCM) are mathematical algorithms that represent the Earth's climate system. These models are at the upper end of the hierarchy of climate models, they are coupled (atmosphere-ocean and soil) and they predict changes of the variables in a longer time. The mathematical expressions that make up a GCM can be analyzed separately within the three main parts of which these models consist: (1) the dynamics of the climate system that describes the large-scale motion of air masses and the transport of the energy and momentum; (2) the physics of the climate system such as transmission of radiation through the atmosphere, thermodynamics, and evaporation; and (3) other factors such as ocean-atmosphere interaction, topography, and parameters that represent vegetation dynamics. These expressions are based on physical laws such as energy and mass conservation as well as empirical relationships based on observed characteristics and trends, such as formulas that relate temperature and humidity to cloud formation” (IPCC, 2007).

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