CMI's goal is to develop an efficient coupled climate model that can be integrated
over many thousands of years for the purpose of long-term climate
Recognizing that the atmosphere and ocean are governed by equations that are
isomorphic to one another, we have built a coupled climate model
based on a single dynamical core - MITgcm. Separate atmospheric and oceanic models are rendered by use of
appropriate physics overlaid on the dynamics.
our approach include:
The dynamical core of
MITgcm exploits the
isomorphism between the equations of motion and boundary conditions that govern the atmosphere and ocean, in pressure (p) and height coordinates (z) respectively.
The vertical coordinate (generic name "r") is scaled by the total fluid column thickness yielding a modified r* vertical coordinate analogous to the atmospheric
Eta coordinate. Combined with the
finite volume method and a
cell representation of topography, the method remains accurate near steep topography.
expanded cubic grid provides a global coverage of the sphere with a relatively uniform
resolution (2.8 degree at the equator) and is used in both
atmosphere and ocean, thus avoiding the problem of convergence or
meridians as the pole is approached. Careful discretization allows
one to accurately treat the whole domain, including the eight singular points at the corner of the cube.
The use of the same horizontal grid simplifies the coupling procedure,
and conservation properties of the coupled model. The 2 components exchange fluxes and surface fields through a single processor coupling interface, using
An atmospheric physics package of intermediate complexity (called
2003) enable extended (100's to
1000's of years) integrations to be
carried out. Although highly
idealized the simplified atmospheric
model captures many realistic
features of atmospheric circulation. Other components include a simple
land model (2 levels), an
instantaneous runoff scheme and
The model runs efficiently on a
local PC cluster
enabling thousands of years of integration to be carried out in days.
J., D. Ferreira, J-M Campin and D. Enderton (2007): Mean climate
and variability of the atmosphere and ocean on an aqua-planet:
J. Atmos. Sci:DOI: 10.1175/2007JAS2226.1
Adcroft, A., J-M Campin, C. Hill and J. Marshall (2004)
Implementation of an atmosphere-ocean general circulation model
on the expanded spherical cube. Mon. Wea. Rev., 132 (12),
Marshall, J. A. Adcroft, J-M Campin and C. Hill (2004)
Atmosphere-ocean modeling exploiting fluid isomorphisms.
Mon. Wea. Rev., 132 (12), 2882-2894
Hill, C., Campin J-M, Marshall, J. and P. Heimbach, 2004:
Overview of the Formulation and Numerics of the MIT GCM.
Proceedings of the ECMWF seminar series on Numerical Methods,
Recent developments in numerical methods for atmosphere and
ocean modelling, 139-149.