ESSAY: Model interpretation of climate signals: an application to the Asian monsoon climate - The Global Climate System: Patterns, Processes, and Teleconnections - page 292

Figure 9.2 An illustration
of the model grid and basic
physical processes in a
climate model consisting of
the atmosphere, ocean, and
land. (Reproduced from
McGuffie and Henderson-
Sellers 2001: Copyright John
Wiley & Sons Ltd., with
permission)
climate modeling. Our knowledge of the physics of the Earth system still
needs to catch up with the advances in computer technology. At a more
fundamental level, climate signals at the regional and subregional scale
may be inherently chaotic and therefore unpredictable. Even if the local
signals are there, climate information downscaled from global climate
models may be masked by large random local fluctuations. To unmask the
regional and subregional scale signals from noise, a number of modeling
strategies have been adopted.
9.2.2 Elements of a climate model
A climate model is derived from an atmospheric general circulation model,
with a dynamical core consisting of a set of primitive equations for the
atmospheric state variables such as temperature, pressure, wind, and water
vapor, which govern the fluid motions, thermodynamics, and conservation
properties for fluid motion of air parcels in the troposphere and stratosphere
on the rotating Earth. The equations are extremely complex and can only be
solved numerically on a horizontal grid system with different vertical levels
(see Figure 9.2 ).
The AGCM is coupled to component models of the oceans, the land, and
the biosphere. Each component model has its own governing equations for its