[MITgcm-support] Open boundary conditions!

[Menemenlis, Dimitris (3248)]

pkg/seaice should behave same as ocean, i.e., periodic boundary condition unless you specify land or obcs at one of the boundaries to break the periodicity.

There is two possible reasons for grid points with temperatures under freezing:

1. if the supercooled temperature occurs below the surface layer, there is no mechanism in pkg/seaice right now to form seaice below the surface
(there is an old flag useOldFreezing that will do this, but not in a conservative way).  This is a bug in code that eventually needs to be fixed, especially now that we are starting to work with ice shelf cavities, i.e., ice should be allowed to form at depth and then rise to the surface.

2. pkg/seaice has variables SEAICE_availHeatFrac, SEAICE_gamma_t, and SEAICE_gamma_t_frz that control how quickly the surface level is restored to freezing temperature when there is sea ice in a grid box.  If you set any of the above three values in data.seaice, then you will allow an ocean grid box with sea ice that is not at freezing point.

On Jun 4, 2010, at 5:01 AM, Ertyy wrote:

> Hi Nicolas:
>     Thank you for your reply! I think it is not the same situation for the sea ice module,so how can I configure an ice-ocean model with period boundary conditon for sea ice? It is my mistake for the freezing tempareture, some grids with strong horizontal temp gradient were generated when preparing the initial conditions from SODA data, which induced the instability, but with no problem when using the ECCO reanalysis. So I think it is a interpolation problem. 
> Best wishes,