[MITgcm-support] global 4deg verification

[samar khatiwala]

Chris, thanks for the reply.

So just to be clear, I should:
  1) run model with deltaTmom = 1200.0, deltaTtracer= 43200.0,
     until close to equilibrium
  2) run syncronously with deltaTmom=deltaTtracer=3600.0, until
     equililibrium is reached

You mention that there are different stability limits for sync and async
integrations. Does that mean, an asyncronous run with deltaTmom=3600
and deltaTtracer= 43200 will be unstable? I know this is a black art,
but it does seem a bit curious. Can you please point me to references
to this issue?

Thanks, Samar

On Sat, 22 Jan 2005, chris hill wrote:

> Hi Samar,
>
>   For a seasonal experiment you should change time steps to be the same.
>   A 3600s timestep should be possible for the seasonal run. The 1200 sec
> is used to allow a longer async ratio, but for a synchronous run the
> stability limits are different so a one hour dt should work.
>
> Chris
> samar khatiwala wrote:
> > Hello
> >
> > I have a query about verification/global_ocean.90x40x15
> >
> > As shipped, the momentum and tracer time steps in this experiment are set
> > to different values in 'data':
> >
> >  deltaTmom = 1200.0,
> >  deltaTtracer= 43200.0,
> >  deltaTClock = 43200.0,
> >
> > Is this because the default is asynchronous time stepping for more rapid
> > spin up? Once the model spins up to equilibrium, do I set deltaTtracer,
> > deltaTClock, deltaTmom equal to each other? I have read (Danabasoglu et
> > al) that in a seasonally forced model, the final spin uip must be done
> > with synchronous time stepping. Can I set all these deltaT's to 43200.0
> > sec without the model blowing up? Or does the CFL limit the time step to
> > 1200.0 sec.
> >
> > Thanks, Samar
> > _______________________________________________
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> > MITgcm-support at mitgcm.org
> > http://dev.mitgcm.org/mailman/listinfo/mitgcm-support
> >
>
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