[MITgcm-support] advection scheme for T/S

[Martin Losch]

Samar,
beats me, but the different advection schemes can be dramatically 
different in their result (have a look at the documentation 
http://mitgcm.org/sealion/online_documents/node80.html ).
Martin

On Sep 24, 2004, at 4:13 PM, samar khatiwala wrote:

> 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
>>
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