[MITgcm-support] advection scheme for T/S

[Jean-Michel Campin]

Hi Samar,


> 1) Does staggerTimeStep affect the ptracers integration in any way (apart
> of course via changing the dynamics)? I don't see it come in anywhere
> in the code except for dynamical quantities but want to confirm.

staggerTimeStep does not affects the ptracers solution.
However, you should not expect identical ptracers results (with
and without staggerTimeStep) after few iterations, because 
of a shift of 1 time step in the flow field that is used to advect
the tracers. So, it might not be very easy to check that it's true.


> 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