[MITgcm-support] close momentum budget

[Matthew Thomas]

Hi Matt

Thanks for the response. Do you know where/how I can access these mode
diagnostics for ecco?

What I want to do is calculate every term in both the zonal and meridional
momentum balance (and then ultimately take their curl to get vorticity
balance). However, the way I understand the situation to be is like this:
The mitgcm configuration for ecco implements the C-D scheme. This means that
2 additional equations are solved in the momentum balance so that D-grid
velocities can be explicitly calculated (for use in the coriolis term)
rather than approximated by four point grid averaging. So in order for me to
exactly close the momentum budget I must have access to these D-grid
velocities.

Matthew


> Hi Matthew
>
> You can exactly close the zonal momentum balance on the c-grid U point
> and meridional momentum balance on the c-grid V point using the mode
> diagnostics (though it isn't exactly trivial).  This is where the
> model closes the budgets.
>
> I'm not sure exactly what you are doing, but sounds like you want to
> check geostrophy.  If you want to move the c-grid velocities to the d
> grid, the default method for the mitgcm is to average the four
> surrounding points.
>
> -Matt
>
>
> > On Jul 6, 2011, at 8:03 AM, Matthew Thomas wrote:
> >
> > Dear all
> >
> > I would like to close the momentum equation in ecco, but this
> > doesn't appear to be possible without the D-grid velocities. Only
> > the C-grid velocities are available for download from the ecco
> > server. Does anyone know how to access the D-grid velocities, or
> > otherwise know how to overcome the problem (which I expect is the
> > same for the unconstrained mitgcm)?
> >
> > Regards
> >
> > Matthew
> >
> >
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