[MITgcm-support] MITgcm 40km resolution Arctic simulation

[Jonny Williams]

Hi again

Good to know that my instructions may be of some use to others so thanks
for that.

I am now 'playing' with the model and have quickly discovered that the
coupling period of the model with atmospheric variables is crucial to when
the model crashes. Specifically the variables...

   - precipperiod
   - atempperiod
   - aqhperiod
   - swdownperiod
   - lwdownperiod
   - uwindperiod
   - vwindperiod

... in the data.exf file (see
here<http://mitgcm.org/viewvc/MITgcm/MITgcm_contrib/arctic/cs_36km/input/data.exf?view=markup>
for
web link).

Thses are currently set to 21600s (6 hours) and sure enough the model
crashes after the first coupling period.

More precisely, the model does not actually crash but rather begin to give
unphysical results, for example in the potential temperature output stream.
I have attached 2 PNG files, one just before and one just after the first
coupling period (40 minute time step). As you can see, the latter contained
lots of small areas of NaNs which show up as blanks in the data. After
this, the whole potential temperature field is NaN but the model itself
does not actually crash and stop running.

I am interested in running the model out for several months or more to get
a good feeling for the circulation patterns which the model gives but at
the moment I am unable to run it out past 6 hours without changing the
coupling period which I'd rather not do if possible (I'd like to keep it
close to the original).

Does anyone have any experience with this type of numerical issue?

Many thanks

Jonny





On 26 October 2013 00:56, Menemenlis, Dimitris (3248) <
Dimitris.Menemenlis at jpl.nasa.gov> wrote:

>  Hi Jonny.  Great that you got it to work.  And thanks for instructions.
>  I have added them to
> http://mitgcm.org/viewvc/MITgcm/MITgcm_contrib/arctic/cs_36km/readme.txt
> for future reference and as a text file so they can more easily be
> modified and change-tracked.
>
>  Cheers
>
>   Dimitris Menemenlis
>
>  On Oct 24, 2013, at 9:01 AM, Jonny Williams wrote:
>
>  Hi there
>
>  I have put a detailed guide on how to get the Arctic regional model
> working here<http://www.paleo.bris.ac.uk/~ggjhtw/MITgcm_cs_36km_guide.pdf>.
> Many thanks again to many of you for your help, particularly Dimitris,
> Patrick and Renske.
>
>  Jonny
>
>
>
>


-- 
Dr Jonny Williams
School of Geographical Sciences
University of Bristol
University Road
BS8 1SS

+44 (0)117 3318352
jonny.williams at bristol.ac.uk
bit.ly/jonnywilliams
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