[MITgcm-devel] obcs in seaice dynamics

[Jean-Michel Campin]

Hi,

I have added a new implementation of OBCS in seaice-dyanmics.
and kept the old one with #define OBCS_UVICE_OLD.
Will switch seaice_obcs test exp to use the new version soon.

I did not implement any of the OBCS_SEAICE_* "experimental"
options in the new version:
- some may not be really used (SMOOTH_UVICE_PERP, SMOOTH_UVICE_PAR)
- a COMPUTE_UVICE equivalent would need to be really different 
  (+would be better in a separated obcs_seaice_calc.F S/R) and I 
  don't know what it should be.
- can certainly put back AVOID_CONVERGENCE in obcs_adjust_uvice.F,
  but one thing I noticed in my simple test was that in the old version,
  the zero seaiceMaskU,V @ Southern & Western boundaries was
  slowing down the ice velocity near the boundaries and generating
  some divergence/convergence. So may be we don't need anymore
  this AVOID_CONVERGENCE piece of code.

I also had to put some masking in the water-drag coeff in order
to get a valid wind-stress at the open-boundary. The wind stress
at the open-boundary is not used for ocean dynamics but is used
in vertical mixing scheme (KPP, GGL90, ...), so better to be right.

And regarding seaice_obcs test exp., it's still not "clean"
(meaning some value @ Western Boundary can influence the solution
at the Eastern boundary, and results will change if OBCS_uvApplyFac
is set to zero), but this is due to KPP and not to seaice.

Cheers,
Jean-Michel