[MITgcm-devel] FREEZE & EXTERNAL_FORCING_SURF

[Dimitris Menemenlis]

Jean-Michel et al., I apologize for trouble I caused.

Yes go ahead and undo changes (there is a pre and post tag) or put on a
separate branch as needed.

A few comments:

1) The change I made last night should not have "any" impact on the
thermodynamic sea-ice package.  If you follow the logic, if ICE_FORCING
is called then neither EXTERNAL_FORCING_SURF nor FREEZE are called.  So
these changes should not affect any of the work that Jean-Michel is
doing.  If they do, then I did something wrong.

2) To work correctly in conjunction with KPP package, the
thermodynamic sea-ice package, and in particular ICE_FREEZE, should be
modified in same way that freeze.F has been modified or that pkg/seaice
is set-up.

3) If you set  allowFreezing=.FALSE., then there is no change in
before/after results for the three global_* experiments that have been
affected.  I believe that this should also be the case for the adjoint
experiments, but I don't know for sure.  In any case, for adjoint
experiments, you almost certainly want to have allowFreezing=.FALSE.

4) It is unphysical, and also causes headaches when you are trying to
keep track of heat input in the model, for FREEZE to operate on a 3-D
field, rather than just at the surface.  The change I checked in last
night resets values less than -1.9 in full 3-D field only during first
model time step and after that operates only on surface.  Model physics
should kick in to make sure that you don't get large negative values
below the surface after that.

5) It's really nice to hear from Alistair at last!!!  It looks like the
only way to get his attention is to do something stupid on the CVS tree
;-)  (Actually I did e-mail Alistair and the list about a month ago that
this change was needed but never got any feedback for or against this
plan.)

6) I agree with Chris that we need a better plan.  Just let me know what
you decide and I will follow the rules.  

D.

-- 
Dimitris Menemenlis <menemenlis at jpl.nasa.gov>
Jet Propulsion Lab, California Insitute of Technology
MS 300-323, 4800 Oak Grove Dr, Pasadena CA 91109-8099
tel: 818-354-1656;  fax: 818-393-6720