[MITgcm-support] Hydrostatic as grid approaches isotropic?

[Jody Klymak]

Hi All,

I have been banging my head against a wall with a simulation where dz  
\approx 2 m and dx \approx 5 m (there is some telescoping away from my  
topography and with depth).  I was running with  
nonHydrostatic=.FALSE.  I expected mode-1 internal waves to zip along  
at 1 m/s, but the fastest I was getting was 0.1 m/s.  I thought it was  
my stratification etc etc.

Then, or fun, I changed dx to 50 m.  Now I get 1 m/s mode-1 waves and  
all is fine.  Is this a known feature of the code?  No doubt an effect  
I should have learnt about somewhere...

I include the pressure solving parts of my data file; maybe I'm doing  
something wrong in here.  Note I use linear free surface because I use  
Orlanski BCs. (ahem, though I really don't as I have a big sponge in  
there.  I really only use the Orlanski code to set OBNu, OBNv, etc, so  
if going to a non-linear surface works with OBCs then I can make the  
effort).

Thanks for any pointers....

Cheers,  Jody


  gravity=9.81,
  gBaro=9.81,
  rigidLid=.FALSE.,
  implicitFreeSurface=.TRUE.,
  eosType='LINEAR',
  nonHydrostatic=.FALSE.,
# minimum cell fraction.  This reduces steppiness..
  hFacMin=0.1,
# implicSurfPress=0.5,
# implicDiv2DFlow=0.5,
# nonlinFreeSurf=3,
# hFacInf=0.2,
# hFacSup=1.8,
#  exactConserv=.TRUE.,
   implicitDiffusion=.TRUE.
   implicitViscosity=.TRUE.
# Superbee on:
  tempAdvScheme=77,
  staggerTimeStep=.TRUE.,




--
Jody Klymak
http://web.uvic.ca/~jklymak/