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A novel feature of MITgcm is its ability to simulate, using one basic algorithm,
both atmospheric and oceanographic flows at both small and large scales.
Figure 1.4 shows an instantaneous plot of the 500
temperature field obtained using the atmospheric isomorph of MITgcm run at
resolution on the cubed sphere. We see cold air over the pole
(blue) and warm air along an equatorial band (red). Fully developed
baroclinic eddies spawned in the northern hemisphere storm track are
evident. There are no mountains or land-sea contrast in this calculation,
but you can easily put them in. The model is driven by relaxation to a
radiative-convective equilibrium profile, following the description set out
in Held and Suarez; 1994 designed to test atmospheric hydrodynamical cores -
there are no mountains or land-sea contrast.
Figure 1.4:
Instantaneous plot of the temerature field at 500mb
obtained using the atmospheric isomorph of MITgcm
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As described in Adcroft (2001), a `cubed sphere' is used to discretize the
globe permitting a uniform griding and obviated the need to Fourier filter.
The `vector-invariant' form of MITgcm supports any orthogonal curvilinear
grid, of which the cubed sphere is just one of many choices.
Figure 1.5 shows the 5-year mean, zonally averaged zonal
wind from a 20-level configuration of
the model. It compares favorable with more conventional spatial
discretization approaches. The two plots show the field calculated using the
cube-sphere grid and the flow calculated using a regular, spherical polar
latitude-longitude grid. Both grids are supported within the model.
Figure 1.5:
Five year mean, zonally averaged zonal flow for
latitude-longitude simulation (bottom) and cube-sphere simulation(top) using
Held-Suarez forcing. Note the difference in the solutions over the pole -
the cubed sphere is superior.
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Next: 1.2.2 Ocean gyres
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