[MITgcm-support] how to control obcs balance flow ?

[Matthew Mazloff]

Hello

I correct OBCS as part of preprocessing and don't rely on ALLOW_OBCS_BALANCE.

Basically you know the inflow/outflow that you want -- so correct your prescribed obcs to have that magnitude inflow.

E.g. if you have a solution from another model that you are gonna make your southern boundary, first interpolate that field to your new model grid. Then make the net prescribed flow through a part of that (e.g. over each 1 degree section) to be the exact same as the original. This usually requires a perturbation to the velocity of about .001cm/s. But if you don't make that correction SSH will run away from you….so its a vital correction.

Matt


On Apr 16, 2014, at 7:39 PM, 李志远 <oceanlizy at 163.com> wrote:

> From: Li zhiyuan <oceanlizy at 163.com>
> >To: MITgcm <mitgcm-support at mitgcm.org>
> >Subject:"how to control obcs balance flow ? "
> Dear MITgcm users:
>       my model has two open boundarys in south and east . I have "#define ALLOW_OBCS_BALANCE " in the OBCS_OPTIONS.h  , but the rusults revealed that  ssh is very high , even up to 2 m !!  I think it is because  the flow in and out  at open boundarys  are not balanced ,so ssh is anomalous. How to control  balance flow  at open boundarys ? 
> Thank you for your quick reply !
> Yours  Li zhiyuan
> Best regards  ! 
> 
> 
> 
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