[MITgcm-devel] sea ice diagnostics

[Jean-Michel Campin]

Hi Martin,

I would think it would be simpler to move the seaice-dynamics diagnostics to seaice_dynsolver
(unless there is a serious issue with that);
the story with segFlag is more to accomodate the Ocean staggered time-stepping and
stay consistent with it.

Cheers,
Jean-Michel

On Tue, May 05, 2020 at 06:07:56PM +0200, Martin Losch wrote:
> Hi Jean-Michel,
> 
> thanks, that???s what I thought.
> I will try this: 
> - pass seqFlag to seaice_diagnostics_state and call only for segFlag < 2
> - have state variable filled for seqFlag=0
> - have other variables like sig1/2 and my new energy diagnostics etc filled for sigFlag=1, because they all require stress and strain, so that it???s good to have them filled together with sig1/2 (but really, it should be done in seaice_dynsolver, shouldn???t it?)
> - there are more energy diagnostics that require local arrays, they will be scattered in pkg/seaice 
> 
> What do you think?
> 
> M.
> 
> > On 5. May 2020, at 18:03, Jean-Michel Campin <jmc at mit.edu> wrote:
> > 
> > Hi Martin,
> > 
> > For state variable diagnostic (as well as directly derived from state vars, e.g., THETASQ),
> > the field is available at any time (since, as a state variable, it is supposed to be in one 
> > of the pickup files) and it can be useful (e.g., when doing a budget, to evaluate the
> > rate of change of a state variable) to have the diagnostic filled up outside
> > the main stepping-forward part, e.g. at the end of the time-step loop or at
> > the beginning of the time-step loop, as currently done from S/R DO_STATEVARS_DIAGS.
> > 
> > But for other intermediate variables, it's better (and easier) to fill-up their 
> > diagnostics from where they are computed. And it avoids the problem of filling
> > up with zero because they have not been computed yet.
> > And regarding pkg/seaice, there are some diagnostics currently filled-up from 
> > seaice_diagnostics_state.F that should not be there, but for some other like
> > SIsig1 & SIsig2, it's not very clear since it depends in using EVP or not
> > (but could have those filled up from different places depending on SEAICEuseEVP).
> > 
> > Cheers,
> > Jean-Michel
> > 
> > On Tue, May 05, 2020 at 01:38:08PM +0200, Martin Losch wrote:
> >> Hi Jean-Michel, and others,
> >> 
> >> we are working on mechanical energy diagnostics for the sea ice model (following Bouchat and Tremblay 2014).
> >> 
> >> While doing so I realized that maybe the diagnostics of seaice are not in the right place:
> >> seaice_diagnostics_state is called from do_statevars_diags when ???seqFlag=0???. this is probably OK for fields like HEFF, AREA, UICE, VICE, but not for derived quantities like SIzeta, SIeta, SIdelta, because they are all 0 in the first time step (after a pickup, say). With that all of SIsig1/2, etc are also not correct because they require zeta/eta from the previous iteration. The same is true for (some of) the energy diagnostics.
> >> 
> >> I am not sure what the correct philosophy is here. The model state variables (diagnostics_fill_state) are all computed at the beginning of the time step, but not always, so it???s a bit difficult for me to diagnose, when what type of variable should be passed to diagnostics_fill.
> >> 
> >> Could you give me some advice?
> >> 
> >> Martin
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