[MITgcm-support] viscosities

[Martin Losch]

with "noise" one normally means some sort of stripes or even  
checkerboard structure overlying the "physical" structure in one or  
more output fields. Usually, velocities are the first field to  
develop noise (if it develops at all). Generally noise points to  
numerical instabilities, which can be overcome by changing  
(increasing) the viscosity and diffusivity parameters. To see an  
example, run one of the tutorials (eg. the barotropic gyre) 1/10 of  
the viscosity (viscAh) or no viscosity for a few time steps and have  
a close look at the solution just before it crashes. You'll recognise  
the when it develops. Then increase the viscosity again until the  
noise vanishes.

Martin

On 13 Jan 2007, at 14:50, Yi HanSoo wrote:

> Hi MITgcm users
>
> I have a simple and basic(?) question while having a look at the  
> mail list.
> Could anyone explain about what it means by "the noise" from the  
> model run and how to check and interpret the noise?
>
> Regrads
>
> -- 
> Lee HanSoo
>
> Ph.D student
> Research Center for Fluvial and Coastal Disasters,
> Disaster Prevention Research Institute, Kyoto University,
> Gokasho, Uji-si, Kyoto, Japan
> 611-0011
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