This will ultimately replace ocean_SIS/OM4_025 and be the foundation for CM4 quarter degree ocean/ice components.

In contrast to ocean_SIS/OM4_025, ocean_SIS2/OM4_025 will:

• consistent and conserving thermodynamics (conserves enthalpy).
• be C-grid, and allow flow through narrow channels.
• have variable bulk salinity, and allow us to have a finite sea-ice salinity (currently sea-ice is fresh).
• use different heat capacities for water and ice.
• use PPM transport of sea-ice.
• allow transport of tracers.

The plan is to create the new ocean_SIS2/OM4_025 and maintain both OM4's while we evaluate them in CORE and CM mode. Once evaluated and rubber-stamped, we'll abandon the SIS1 versions of this experiment, and probably other experiments too.