[MITgcm-support] Orlanski OBCS problem

[Martin Losch]

Hi Pat,

your email implies that you use OBCS with Orlanksi boundary conditions. With open boundaries (especially with the "dynamic" Orlanski radiation conditions), it is usually very tricky to make the model conserve volume, i.e. have a zero net flow across the open boundary conditions, and that very quickly leads to unrealistic sea level change. We have the option to "balance" the flow. Please have a look at the documentation:
<http://mitgcm.org/public/r2_manual/latest/online_documents/node236.html#SECTION00731560000000000000>

Martin

On Jan 3, 2013, at 10:26 PM, Pat Gallacher <patrick.gallacher at nrlssc.navy.mil> wrote:

> I'm am testing a simple wind forced simulation at high resolution, dx=dy=5m, dz=1m with Coriolis forcing using the nonhydrostatic option with no stratification. For the parameters I am using, ustress=0.1, vstress=0.0, Az=3.6e-4, f=6.8e-5, I am getting the correct Ekman depth and velocities. However the sea surface is rising monotonically achieving a height of about 34m in 48 hours. The Orlanski parameters I am using are: Cmax=0.4, cVelTimeScale=12.0.
> 
> Any ideas about the eta issue?
> 
> Thanks,
> Pat
> _______________________________
> Patrick C. Gallacher, PhD
> Oceanographer
> Nonhydrostatic Ocean Modeling
> Naval Research Laboratory
> Code 7331
> Stennis Space Center, MS 39529
> Phone: (228) 688-5315
> FAX:   (228) 688-5997
> email:  Patrick.Gallacher at nrlssc.navy.mil
> website: http://www7331.nrlssc.navy.mil/view_project.php?project=nonhydrostatic_dynamics
> _______________________________
> 
> 
> 
> 
> 
> 
> 
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