[MITgcm-devel] wrapping up seaice_growth.F october 2010 revision

[Gael Forget]

Dear all,

Revision 1.89 of seaice_growth.F completes the overall october 2010 revision and merging process. 
After sending this email I will add a summary of the 10/10 revision in tag-index.

If you please, it is time for you to look at the code, and put it to the test. 
Hopefully we won't discover too many mistakes of mine. Please let me know if you do.

In my view, the next phase consists in freezing seaice_growth.F (the code I mean :-) ) for a while, 
to take the necessary time (a week or two?) to understand and evaluate the code as it stands now. 

The routine has two branches (ifdef/ifndef SEAICE_GROWTH_LEGACY) that are meant 
to cohexist, at least for a while. For the most part they are identical. Only a 
few code blocks are switched ON or OFF by means of SEAICE_GROWTH_LEGACY.

The 'legacy' branch remains the default for now (see #define SEAICE_GROWTH_LEGACY 
at the top of the routine). It should give results that are very similar to v1.70.
This branch is meant to stay the way it is, except for potential bug fixes. 

So, please keep new stuff within "#ifndef SEAICE_GROWTH_LEGACY" brackets, 
namely within the other ('evolution') branch. No need to rush it anyway.

The 'evolution' branch is meant to eventually become the default, but only once it 
has been sufficiently tested, and I have gotten feedback -- I wont rush it. 
'evolution' contains the two "_if.F" pieces. Except for that, the main deviation 
from 'legacy' is the treatment of pathological cases. It does, or will, 
ensure closed budgets. It takes place at the beginning of seaice_growth.F, 
right after advdiff, which is where pathological cases can come from. There is 
no reason why the thermodynamic code itself would lead to pathological cases. 
We just have to make it rigorously correct -- if the code is not already such, 
it will be.

With my set-up I plan to do few-years-long runs to test the code, using
	v1.70 (legacy, pre  10/2010 revision)
	v1.89 (legacy, post 10/2010 revision)
	v1.89 (evolution' #undef SEAICE_GROWTH_LEGACY in seaice_growth.F)
	v1.11 of seaice_growth_if.F
and compare results. It would be great if some of you did something like 
this with your own set-up of choice, and let me know how it went.

Cheers,
Gael

ps: Martin, I will reply to your questions in a separate email.