[MITgcm-support] partial cells and model stability

[Matthew Mazloff]

Hello support line,

I am looking for information regarding partial cells and model 
stability.  I have run the model with smooth bathymetry and coarse 
bathymetry and there is little difference with model stability. The 
majority of my abyssal depth levels have delZ=250.0 and when I first 
turn on partial cells and leave hFacMindz = 250.0 the model is stable.  
When I turn hFacMindz=225.0 the model becomes significantly less 
stable.  My vertical stability parameters are well within a safe range 
so that I do not believe the change in dz from 250 to 225 is causing a 
problem.  The model is, however, very sensitive to viscAh.  For my 
quarter degree model I currently have viscAh set to 6.65E3 and making it 
any larger or smaller requires me to shorten the time step (current 
timestep=1140sec).  I would greatly appreciate any comments.

Thanks for your advice,
Matt

PS> I am running with open boundaries but I am running on a C-grid and I 
have made sure that the open boundary and the adjacent cell has the same 
bathymetry level.  Are there any issues regarding partial cells and open 
boundary conditions that I should be aware of?