[MITgcm-support] THSIce noisy/unphysical output

[Chris Horvat]

Just to keep this going, this is similar to a problem I had earlier this
year. All of the tiles in the simulation were the same even without any
packages turned on.

That link can be found here:
http://dev.mitgcm.org/pipermail/mitgcm-support/2014-March/009002.html which
suggests some help.

I was able to solve the problem by changing FFOPTIM in build-options to O0
from O4 or some such thing, which slows down the gcm execution time
significantly, but not terribly. After speaking with Patrick I was unable
to replicate the error... which is fortunate and unfortunate in different
ways. Perhaps just re-making the GCM may help.

Since I had this problem, too, I figured we could look try to resolve what
the underlying issue is!

Chris




On Wed, Nov 12, 2014 at 5:57 PM, Jean-Michel Campin <jmc at ocean.mit.edu>
wrote:

> Hi Patrick,
>
> Could you send (in attachement) the full set of parameter files
> (main parameter file "data" and all the other data.* files)
> as well as SIZE.h (since you try several tile domain decomposition)
> that correspond to the figure you sent ?
> Right now, it's difficult to guess where the noise comes from.
>
> Also, on the figure you sent, can you confirm that the amplitude of
> the noise in ice thickness is about 0.0172 - 0.0156 = 0.0016 m ?
>
> Cheers,
> Jean-Michel
>
> On Fri, Nov 07, 2014 at 05:05:21PM +0000, Patrick Watts wrote:
> > Hi MITgcmers,
> >
> > I have been running the model in a coupled setup, with ocean, a CheapAML
> atmosphere, and using the THSIce model. The resolution is very high (20m in
> all directions) and the setup is idealised, essentially a doubly periodic
> box.
> >
> > The output of the ice model is extremely noisy, with a pattern repeating
> for each tile (see attached for an example). I have tried changing the time
> step, minimum ice thickness, and mask of the ice model, as well as the
> fortran optimisation, number of tiles, and the number of grid points
> overlapping between tiles - the pattern has changed and there can be larger
> variations in ice thickness overlying it, but nothing so far has actually
> got rid of it.
> >
> > Absolutely any suggestions of what the root cause could be or how I can
> try to get rid of it are appreciated.
> > Thanks,
> > Patrick
>
>
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>
>
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