The basic features of the 1999 version of the Atmosphere-Ocean Model
are as follows:

Resolution
----------
1.  5 degrees in longitude by 4 degrees in latitude.
2.  Atmosphere uses 9 layers everywhere.
3.  Ocean uses up to 13 layers; approximate thicknesses in meters are
      12, 18, 27 ... 1557 (geometric series with ratio 1.5).
4.  Prognostic gradients of heat, water vapor, and salt increase
      effective resolution.
5.  Atmospheric condensation and ocean vertical mixing are performed on
      2.5 by 2 degree horizontal resolution.

Atmosphere
----------
1.  Dynamics of mass and momentum uses Arakawa's C grid scheme.
2.  Advection of heat and water vapor uses Linear Upstream Scheme.
3.  Condensation is performed by penetrating moist convection and by
      large scale condensation.
4.  Cloud optical depths depend on square root of condensate leaving a
      layer.
5.  Radiation use all significant gases, aerosols and cloud particles
      with 6 spectral intervals for solar and 25 spectral domains for
      thermal.
6.  Simplified drag law fluxes are used in complicated implicit time
      scheme for determining surface fluxes.
7.  Abramopoulos' ground hydrology scheme is used.

Ocean
-----
1.  Dynamics of mass and momentum uses modified C grid scheme.
2.  Advection of heat and salt uses Linear Upstream Scheme.
3.  Ocean vertical mixing uses KPP scheme of Large et al.
4.  Mass is conserved, not volume; free surface height.
5.  12 subresolution straits.
6.  No explicit horizontal diffusion of heat or salt.

Sea Ice
-------
1.  Each box may have fractional sea ice cover with variable depth.
2.  Sea ice velocity is accelerated by 6 terms each source term time
    step: atmospheric stress, ocean drag, Coriolis force, surface
    pressure and ocean tilt, internal sea ice pressure, and island
    blocking factor.
3.  Uses 4 thermal layers.
4.  Forms on open ocean with .4 meter thickness.
5.  Thickens by compacting of snow or freezing of ocean below.
6.  Melts from surface fluxes (insolation) or from warm ocean.