[MITgcm-support] numerical instability in a non-hydrostatic simulation

[Jean-Michel Campin]

Hi Guangyu,

I don't know where the noise comes from, but just to get an idea of resolution
and domain size: 
what are the value of Nx,Ny,Nr ? (from the parameter file "data", it's not obvious 
since tRef,delX,delY, delR are set from a bin file).
And are you using a variabl resolution in X ? in Z ?

Cheers,
Jean-Michel

On Thu, Jun 11, 2026 at 09:18:01AM -0700, Guangyu Xu wrote:
> Hello fellow MITgcm users,
> 
> I have been running MITgcm simulations to investigate the wakes behind
> surface platforms. Attached are a plot of the vertical temperature
> cross-section from a non-hydrostatic run and the runtime model settings.
> The two vertical bars near 0 and 0.5 km w-e distances are the subsurface
> structures of two platforms. The initial temperature field is horizontally
> homogeneous. The model forcing consists of a constant eastward flow of 0.2
> cm/s. There is no surface forcing or Coriolis.
> 
> I noticed that the oscillations of isotherms around 0.5 km w-e distance
> have very short wavelengths, which span only two grid cells. These
> oscillations are numerical artifacts, and they are not present in the
> results of hydrostatic runs.
> 
> I am interested to know if any of you have seen similar artifacts in
> non-hydrothermal simulations. Any suggestions on how to eliminate or reduce
> these numerical noises would be greatly appreciated.
> 
> Many thanks!
> Guangyu



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