[MITgcm-support] only eta as open boundary ?

[kaveh Purkiani]

Dear Martin,

I use nonlinearFreesurf in my configuration similar to as sinusoidal
elevation (simple M2) at BC. Also the  nonlinFreeSurf = 1 at data namelist.
Should not this work? and show non-zero elevation inside the model as well
as boundaries?

The method for converting the elevation into bartropic velocities seems to
work, but I wanted to apply a realistic condition to the model ( components
of M2, M4, S2 and O1 ) therefore, using eta BC seems to be more accurate.

regards

Kaveh.


On Mon, Feb 1, 2016 at 10:23 AM, Martin Losch <Martin.Losch at awi.de> wrote:

> Kaveh,
>
> you probably use a linear free surface in your model configuration? With a
> ***linear*** free surface, the open boundary conditions for Eta have no
> effect (basically, there are none to be specified). But your method of
> converting the elevation into bartropic velocities seems to work, doesn’t
> it?
>
> Otherwise you need to use a non-linear free surface, which will make the
> experiment more complicated.
>
> Martin
>
> > On 30 Jan 2016, at 20:50, kaveh Purkiani <kavehpurkiani at googlemail.com>
> wrote:
> >
> > Hi MITgcm users,
> >
> > I have been trying to use eta as the only boundary condition in
> > a configuration.
> >
> > below you see the relative part of configuration regarding the bcs at
> data and data.obcs
> >
> > data
> >
> >  periodicExternalForcing=.TRUE.,
> >  externForcingPeriod=900.,
> >  externForcingCycle =43200.,
> >  &
> >
> >
> > data.obcs
> >
> >  OBCSfixTopo=.FALSE.,
> >  OB_Jnorth= 80*-1,
> >  OB_Jsouth= 80*1,
> >  OB_Ieast = 42*-1,
> >  OB_Iwest = 42*1,
> >  useOBCSprescribe = .TRUE.,
> >
> >  OBNetaFile = 'OBNeta.bin', (Nx,time)
> >  OBSetaFile = 'OBSeta.bin', (Nx,time)
> >  OBWetaFile = 'OBWeta.bin', (Ny,time)
> >  OBEetaFile = 'OBEeta.bin', (Ny,time)
> >
> > The boundary conditions are obviously read in (only at boundaries output
> shows identical to what is prescribed as boundary condition),
> >  but they are not applied inside the domain. Except the boundaries, rest
> of the domain does not show any elevation.
> >
> > When I convert the sea surface elevation (eta) into barotropic velocity
> and prescribe the OB(N,S,E,W)(u,v) and no elevation at boundaries, it works
> > properly, with meaningful eta, zonal and meridional values.
> >
> > I appreciate any suggestions.
> >
> > regards,
> >
> > Kaveh.
> >
> >
> >
> >
> >
> >
> > _______________________________________________
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> > MITgcm-support at mitgcm.org
> > http://mitgcm.org/mailman/listinfo/mitgcm-support
>
>
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