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Education -
General
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Written by Mark Chandler and Ana Marti
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Monday, 06 March 2006 |
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Page 3 of 5
3) "GCM": General Circulation Models,
Global Climate Models
GCMs are Process Models - Simulations are based on fundamental physical equations and, therefore, GCM output is examined not only to establish a Cause and Effect relationship, but to explore the mechanisms by which the Earth's climate system operates. The "Primitive Equations" calculate Temperature (T), Pressure (P), Winds (U,V,W) and Specific Humidity (Q) and a wide variety of empirically-based, or theoretically-based equations are used to "parameterize" other processes (e.g. cloud formation, radiation interactions, etc.). that are not described explicitly via the fundamental physical equations.
In the climate system there is rarely a simple cause and effect relationship between phenomena. Instead, forcing mechanisms set into motion a series of feedback processes that eventually alter the equilibrium of the climate. Often, the feedbacks themselves are more powerful agents of change than the original forcing.
Using a GCM on a Supercomputer: Model rundecks
Unix scripts, like the model rundeck shown below, are used to initiate climate simulations on supercomputers and powerful unix workstations. They are efficient for scientists and programmers, but they assume a great deal of prerequisite knowledge regarding the computer model and require that the user have significant computer programming skills.
 A Rundeck Script for the GISS GCM
Using a GCM on a Desktop Computer: The EdGCM Interface
 EdGCM puts control of a GCM in your hands via point and click interfaces
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