Large and complex computer programmes that attempt to mathematically simulate global climate. They are based on mathematical equations that seek to represent the physical processes that govern the earth-atmosphere system. (See “Climate Models”). (Source: International Petroleum Industry Environmental Conservation Association (IPIECA), Climate Change A Glossary of terms, 3rd Edition, January 2001. London, 2001.)

Three dimensional computer simulations of climate and weather which, through calculations, are used to investigate gravity wave fields. The models may help to predict atmospheric chemistry distribution and meteorological trends for the future. [Atmospheric Change; Graedel, T. E.; W. H. Freeman and Company; New York; page 327-8; 1993.] [Coupling Processes in the Lower and Upper Atmosphere; Edited by Eivind Thrane; Kluwer Academic; Boston; page 161; 1993.

Hydrodynamic models of the atmosphere on a grid or spectral resolution that determine the surface pressure and the vertical distributions of velocity, temperature, density, and water vapor as functions of time from the mass conservation and hydrostatic laws, the first law of thermodynamics, Newton's second law of motion, the equation of state, and the conservation law for water vapor. Abbreviated as GCM. Atmospheric general circulation models are abbreviated AGCM, while oceanic general circulation models are abbreviated OGCM.