[MITgcm-support] boundary conditions, in general

[Haferman, Jeffrey (Jeff) (CIV)]

Thank you all.  I know periodicity in the vertical seems like a strange
request, but the scale of the modeling that I am doing is just a few
meters and my model "doesn't know" about the surface or bottom of the
ocean.  I do need to implement periodic BCs in the vertical, so it
sounds like I will have to make some modifications to the code...

Jeff



-----Original Message-----
From: mitgcm-support-bounces at mitgcm.org
[mailto:mitgcm-support-bounces at mitgcm.org] On Behalf Of Martin Losch
Sent: Friday, December 22, 2006 1:34 AM
To: mitgcm-support at mitgcm.org
Subject: Re: [MITgcm-support] boundary conditions, in general

Hi Jeff,

Helen is right: the periodicity is handled in the "exchange"  
routines. Whenever you see a _EXCH_XYZ_RL (uVel,myThid)
(e.g. in model/src/do_fields_blocking_exchanges.F) the tile edges are  
updated including periodic (wrap around) boundary conditions. You  
supress those by inserting a grid cell row and/or column that is  
land, eg. in matlab code:
h=-5000*ones(nx,ny);
h(:,end) = 0;
h(end,:) = 0;
is a closed box with a depth of 5000 meters.

periodicity in the vertical is not supported, there is always  
"bottom" at one end and free surface at the other end and the  
boundary conditions are tailored to this situation. In particular  
there are no "overlaps" in the vertical direction. After all, it's an  
ocean model and the ocean is hardly ever periodic in z (o:

Martin

On 21 Dec 2006, at 18:15, helen hill wrote:

> Hi Jeff
>
> I think the model is doubly periodic by default so you may not find  
> anything to indicate that the model is being made to be doubly  
> periodic.
>
> As to your second question - I'm not sure - maybe someone else knows
>
> Helen
>
> On 12/21/06, Haferman, Jeffrey (Jeff) (CIV) <jlhaferm at nps.edu> wrote:
>
> Hi -
> I'm looking at exp5 supplied with MITgcm (imhomogeneously forced ocean
> convection in a doubly-periodic box).
>
> I've spent quite a bit of time looking through the documentation  
> and the
> input/data file, and it's not clear to me what settings are making the
> lateral (x, y) boundary conditions to be periodic.  Can someone  
> clarify?
>
> Also, is it possible to make the boundary conditions periodic in the
> vertical (z, or in the input code "r") dimension?
>
> Thanks,
> Jeff
>
>
>
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