[MITgcm-devel] thsice + seaice

[Martin Losch]

FYI,
I have put a quick and rough comparison of the seaice and thsice  
THERMODYNAMICS here:
<http://mitgcm.org/~mlosch/cmpice.tar>
This is a spinup-run that I have done here at AWI on the "NAOSIM"  
1/4th degree grid, shown are monthly means effective thickness,  
concentration, "salt flux", and a histogram of ice thickness  
differences after 10 years of integration. It's immediately clear  
that thsice produces more ice and in particular in summer, the ice  
concentration is higher (which is good, because in general, the  
summer ice concentration is underestimated by a lot of models that  
get the winter concentration right, see AOMIP paper C04S11 in JGR by  
Johnson et al, 2007, doi:10.1029/2006JC003690). Also the ice extend  
is larger in thsice, and may require some tuning. I don't understand  
why the "salt flux" is so different, maybe I am not plotting the same  
thing. Also, with thsice, there are problem near the open boundary in  
the Bering Strait/Sea, which I don't want to investigate now.
In general, the thsice seems to work nicely (although I has a  
significant portion of code that does not vectorize and thus is a  
pain in the ... for me, I'll look into that sometime), and I hope  
that Dimitris will get similar results. However there are always  
plenty of
BBerr - Bug: IceT(1) > Tmlt 239  32  1  1 -5.376776E-02 -5.400000E-02
which I choose to ignore.

One problem, which I have not yet solved (and I guess that Dimitris  
is also struggling with), is that the model crashes after 1 timestep  
when I specify initial conditions like this:
> thSIceFract_InitFile='ice_conc.bin',
> thSIceThick_InitFile='ice_thick.bin',
Maybe I am overlooking something here? I faintly remember that I need  
to specify not only thickness and concentration, but also some  
initial values for entalphy and snow? Is that true?

Martin

On 29 Apr 2008, at 16:36, Martin Losch wrote:

> Hi there,
>
> I just had a chat with K+K (Frank Kauker/Michael Karcher) who work  
> on the Arctic with NAOSIM. They have made a lot of progress in  
> generating the adjoint to this model, so that they can look at real  
> science questions. Frank show me an extended abstract where they  
> investigate the probably causes of the Sept, 2007 ice minimum with  
> adjoint sensitivities back to March 2007; as far as I could see,  
> it's very nice work, in particular, because it addresses a real  
> question. I see this as an incentive to once again push our efforts  
> (and encourage Patrick to write up his adjoint stuff).  
> Unfortunately, we have been held up by various problems, which I am  
> trying to summarize:
> General: I have updated some figures (JFMuv_*) to reflect the  
> latest runs, I also cleaned up the figs directory on skylla  
> (removed old stuff, that we no longer use)
> - Section 1: Needs a lot of work, maybe Chris can have a look at it?
> - Section 2: Is basically done, except for small bits and details  
> on THSICE, the latter I hope Jean-Michel can provide. I suggest  
> that we use this section to collect all information on the model  
> and then cut later.
> - Section 3: forward integrations: Dimitris and I have finally  
> converged on a set of experiments to analyse, most of which have  
> been done (by D.) but in particular some of the EVP runs are not  
> there, yet. I can't continue with section 3.3 unless they are done.
> - Section 3: I don't know what the status of section 3.1 (bi-polar  
> sea ice from global integration) is. Since I have now a global  
> integration, too, I could use data from that integration to plot  
> ice fields. Dimitris, what's your status here? Do you want me to do  
> this (I have no idea what to plot here, seasonal averages?)?
> - Section 4: Patrick, my last email exchange with you was almost a  
> month ago, when you wanted to rerun some experiments after  
> adjusting SEAICE_gamma_t or availHeatFrac, in order to compare to  
> Ian Femty's code/results, what's the status here.
> - Section 5: (Summary/Conclusions), nothing new so far.
>
> what can we do to push this manuscript?
>
> Martin
>