[MITgcm-support] Re: noise in high resolution run

[Martin Losch]

Hi Michael,

I hope you don't mind that I reply to the support list. I  
particularily like the part of your comment where you say, that obcs  
prescribe type experiments seem to work for you. Very comforting!
But when you say that you've seen noise in the interior in long run,  
did you see that noise near topography or other solid (castellated)  
lateral boundaries?

Martin
On Mar 30, 2006, at 4:59 PM, Michael Schaferkotter (Contractor) wrote:

> martin wrote:
>
> I seem to have a problem with a 1/6 by 1/6*cos(phi) run with open  
> boundaries. The domain is the Drake Passage. A plot of bathymetry  
> and velocities can be found in
> http://mitgcm.org/~mlosch/noise.png
>
> ...
> I wonder if anyone has seen something like this before. What do you  
> think?
>
>
>
> hi martin;
> my first thought was the deltax idea that you discuss.
>
> perhaps you could try removing the 'y-grid varies with y'  
> configuration with a constant dy and see if the problem goes away
> (if it is not too much work)?
>
> would you be able to post a time series animation of the velocities?
>
> might also be interesting to set viscAh=0.0 and see what goes as well.
>
> we had some problems like this with the NCOM (hydrostatic) at one  
> time and tried all sorts of things.
> it turned out to be an indexing problem in the code.
>
> also, we/ve run many obcs prescribe type experiments (with MITgcm)  
> and haven/t seen this near the boundaries, but
> in the interior for long integrations.
>
> michael