doc/overview/global_atmos_hs.rst

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0001 Global atmosphere: â€˜Held-Suarezâ€™ benchmark
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                0003
                0004
                0005 A novel feature of MITgcm is its ability to simulate, using one basic algorithm,
                0006 both atmospheric and oceanographic flows at both small and large scales.
                0007
                0008 :numref:`cubic_eddies_figure` shows an instantaneous plot of the 500 mb
                0009 temperature field obtained using the atmospheric isomorph of MITgcm run at
                0010 2.8° resolution on the cubed sphere. We see cold air over the pole
                0011 (blue) and warm air along an equatorial band (red). Fully developed
                0012 baroclinic eddies spawned in the northern hemisphere storm track are
                0013 evident. There are no mountains or land-sea contrast in this calculation,
                0014 but you can easily put them in. The model is driven by relaxation to a
                0015 radiative-convective equilibrium profile, following the description set out
                0016 in Held and Suarez (1994) :cite:`held-suar:94` designed to test atmospheric hydrodynamical cores -
                0017 there are no mountains or land-sea contrast.
                0018
                0019
                0020   .. figure:: figs/eddy_on_cubic_globe.*
                0021     :width: 60%
                0022     :align: center
                0023     :alt: cubic eddies figure
                0024     :name: cubic_eddies_figure
                0025
                0026     Instantaneous plot of the temperature field at 500 mb obtained using the atmospheric isomorph of MITgcm
                0027
                0028
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0029 As described in Adcroft et al. (2004) :cite:`adcroft:04b`, a â€˜cubed sphereâ€™ is used to discretize the
                0030 globe permitting a uniform griding and obviated the need to Fourier filter.
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0031 The â€˜vector-invariantâ€™ form of MITgcm supports any orthogonal curvilinear
                0032 grid, of which the cubed sphere is just one of many choices.
                0033
                0034 :numref:`hs_zave_u_figure` shows the 5-year mean, zonally averaged zonal
                0035 wind from a 20-level configuration of
                0036 the model. It compares favorable with more conventional spatial
                0037 discretization approaches. The two plots show the field calculated using the
                0038 cube-sphere grid and the flow calculated using a regular, spherical polar
                0039 latitude-longitude grid. Both grids are supported within the model.
                0040
                0041  .. figure:: figs/u_cube_latlon_comb.*
                0042     :width: 80%
                0043     :align: center
                0044     :alt: hs_zave_u_figure
                0045     :name: hs_zave_u_figure
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0047     Five year mean, zonally averaged zonal flow for cube-sphere simulation (top) and latitude-longitude simulation (bottom) and using Held-Suarez forcing. Note the difference in the solutions over the pole â€” the cubed sphere is superior.
                0048