[MITgcm-devel] thsice + seaice

Tue May 6 08:33:18 EDT 2008

Martin,

This BBerr - Bug: IceT(1) > Tmlt 239 32 1 1 -5.376776E-02 -5.400000E-02 
has something to do with the melting point of seaice and the surface temp 
solver (as I think you deduced). It is something I've noticed that seems 
to me at least to be handled somewhat inconsistently in the Winton 
documentation. I think Jean-Michel and I had meant to sort this out at 
some point, but never got around to it.

Bottom line, I wouldn't worry about this error unless you see IceT(1) 
getting positive. I'll talk to Jean-Michel about my thoughts why this is 
occurring and hopefully remove the error message.

Jeff

P.S. On the comparison of seaice and thsice discussion, it would be 
helpful to know what parameters were used in thsice, or at least those 
changed from default. I've used thsice quite a bit (but not with 
dynamics unfortunately) and found the results sensitive to some 
parm choices.)

On Tue, 6 May 2008, Martin Losch wrote:

> Hi Jean-Michel,
> with a running, not-exploding model I still get a lot of "errors" like this 
> one
>> BBerr - Bug: IceT(1) > Tmlt 239  32  1  1 -5.376776E-02 -5.400000E-02
> with IceT(1) getting as high as -1.e-2, but never positive. I wonder if this 
> is anything to worry about, or whether is this an occasional non-convergence 
> of the solver (thsice_solve4temp).
>
> BTW, these multiple write statements in thsice_solve4temp make it impossible 
> to vectorize this routine (the other issue are the called routines that have 
> to inlines). Is there a way to get around these write statements, like 
> enclosing them in #ifdef ALLOW_DBUG_THSICE, since they don't do anything but 
> print out warnings. Or is this package still so unstable that we cannot 
> afford the absense of continuous warnings?
>
> Martin
>
> On 6 May 2008, at 01:51, Jean-Michel Campin wrote:
>
>> Dimitris & Martin,
>> 
>> Good that it's working for both of you.
>> It seems that there is something strange in the initialisation.
>> Don't have time to look at it now, but will at some point.
>> 
>> An other thing:
>> who is supposed to update the output.txt of seaice_obcs ?
>> Otherwise, (since April 26) if something (wrong) happens to this set-up,
>> we will not be able to catch it.
>> 
>> Cheers,
>> Jean-Michel
>> 
>> On Mon, May 05, 2008 at 04:03:46PM -0700, Dimitris Menemenlis wrote:
>>> Martin, now that I have solved my diagnostics problem, I finally also
>>> have a thsice + seaice setup running on the Arctic grid.  To get
>>> around the "BBerr - Bug: IceT(1) > Tmlt 239  32  1  1 -5.376776E-02
>>> -5.400000E-02" errors, I initialized with sea ice thickness only,
>>> i.e., no area and no snow.  Maybe snow plus thickness would have
>>> worked also.  I did not try that combination.  But area plus thickness
>>> initialization did not work at all for me.  D.
>>> 
>>> Dimitris Menemenlis <menemenlis at sbcglobal.net>
>>> 5056 Oakwood Ave, La Canada, CA 91011-2450
>>> tel/fax: 818-790-6735;  cell: 818-625-6498
>>> 
>>> On May 2, 2008, at 6:23 AM, Martin Losch wrote:
>>> 
>>>> 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
>>>>> 
>>>> 
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