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

[Martin Losch]

Hi Li Zhi,

all parameters are nicely described in /model/inc/GRID.h, but probably also in the documentation.

hFacW/S are the hfac’s as the “western” and “southern” face, so at u and v points. The flow through a grid cell face is:

uFlux = uVel(i,j,k,bi,bj)*hFacW(i,j,k,bi,bj)*dyG(i,j,bi,bj)*drF(k)
vFlux = vVel(i,j,k,bi,bj)*hFacS(i,j,k,bi,bj)*dyG(i,j,bi,bj)*drF(k)

Martin

On Apr 27, 2014, at 4:40 PM, 李志远 <oceanlizy at 163.com> wrote:

> HI ,Martin;
>     I have read the dxg,dyg,hfacc,hfacw,hfacs files . I understand what is the meaning of dxg,dyg,hfacc , but I am not clear what is the meaning of hfacw and hfacs .and I am not sure how to use them to calculate total flow out and flow in the open boundarys .Could you tell me something about it ?  It is really some shame to ask such easy questions , but I really need that .....
>  thank  you so much ,sir  !
> YOURS LIZHI 
> 
> 
> 
> 
> >>Date: Wed, 23 Apr 2014 08:35:54 +0200
> >>From: Martin Losch <Martin.Losch at awi.de>
> >>To: MITgcm Support <mitgcm-support at mitgcm.org>
> >>Subject: Re: [MITgcm-support] how to control obcs balance flow ?
> >>Message-ID: <EF678506-3E22-45AA-9C19-72E6CFFCC9C7 at awi.de>
> >>Content-Type: text/plain; charset="utf-8"
> >>
> >>HI Li Zhi,
> >>
> >>I agree with Matt, the best choice is to balance the fluxes during preprocessing. It is a bit tricky, because you need to take into account the exact geometry, i.e. the approrpiate dz, dxg, dyg, hFacS, hFacW. So don?t despair, if it doesn?t work the first time around. You also need double precision for the boundary files, as single precision can already give you some sea level change.
> >>
> >>For completeness: The balancing that you asked about is described here: <http://mitgcm.org/public/r2_manual/latest/online_documents/node236.html>
> >><http://mitgcm.org/public/r2_manual/latest/online_documents/node236.html#SECTION00731560000000000000>
> >>
> >>This method balances the net flow at each time step, which may not be what you want.
> >>
> >>Martin
> 
> 
> 
> 
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