[MITgcm-support] advection scheme for T/S

[samar khatiwala]

Hi Jean-Michel and Martin:

I turned on staggertimestep according to your suggestion. For my
configuration I get practically identical results with this flag ON or
OFF (and tempAdvScheme=30). Incidentally, I only have one active tracer
(T; sBeta=0 and there is no forcing of S) and strong mixing was not the
problem (in comparison with ABII). Indeed, I would say that with DST3 I
get less mixing so the internal wave instability problem was not
of any consequence. So I still don't understand why the steady solution
is so different for the two schemes. Its a bit disconcerting.

Samar

On Tue, 21 Sep 2004, Jean-Michel Campin wrote:

> > 2) Does what you say about using staggerTimeStep with advScheme 77 and 33
> > also apply to advScheme 30?
>
> Yes. those 3 advection schemes don't use the adams-bashforth
> (you can look in STDOUT file: tempAdamsBashforth & saltAdamsBashforth)
> and need a stagger-TimeStep for internal-wave stability.
> I don't know what happens when only 1 active tracer is using
> the AB-II but not the other (depending on the EOS and the kind
> of stratification you have ... ) and it's one of the reasons why
> staggerTimeStep is not turned on automatically (+ historical reason).
>
> Hope this helps.
>
> See you,
> Jean-Michel
>