[Mitgcm-support] Re: FW: grid scale oscillations

[mitgcm-support at dev.mitgcm.org]

Hi,

Looks like the Non-linear flux limiter advection scheme kills them off.

Does this advection scheme work OK with the adjoint?

Thanks

Dan

On Wed, 12 Mar 2003, Chris Hill wrote:

> Dan,
>
>  I'll do a survey of people here and see what they suggest. Meantime,
> any pictures or thoughts on whether noise is related to steep topo.,
> thin shaved cells or at open boundaries or something else etc.... Also
> the values you have in data and data. files might give a clue -
> especially lopping thresholds ( hFacMin etc...).
>
>  Alistair - I remember Jake telling me that you had given him some fixes
> to help with OBCS recently.
>  Jake (who is skiing this week) any comments?
>
> Chris
>
> > -----Original Message-----
> > From: Daniel Lea [mailto:daniel.lea at jhuapl.edu]
> > Sent: Wednesday, March 12, 2003 12:47 PM
> > To: Chris Hill
> > Subject: grid scale oscillations
> >
> >
> >
> > Hi Chris,
> >
> > I spoke too soon last week! I was working with a non shaved
> > cell version
> > of the model I've switched to a shaved cell version and the grid scale
> > oscillations are back. They are not strong and the model runs OK
> > otherwise.
> >
> > As I said my resolution is 1/6 zonal by 1/12 meridional. I've tried
> > playing around with the vertical and horizontal (biharmonic)
> > diffusion and
> > viscosity to no avail. Changing the advection scheme from 2nd
> > order to 4th
> > order is not helpful. I haven't tried a flux limited scheme but don't
> > think that would be good for the adjoint...
> >
> > Should I smooth the topography somehow? (A very basic smoothing didn't
> > help). What about conservation: E.g.  exactConserv or
> > useEnergyConservingCoriolis?
> >
> > Thanks
> >
> > Dan
> >
> >
> >
> >
>