[MITgcm-support] L4rdt

[David Ferreira]

Dimitris Menemenlis wrote:
> David, does necessity to pump up viscA4grid also carry over to 
> viscA4GridMax?
>
> Specifically, for the CS510 configuration we use
>  viscC4Leith=1.5,
>  viscC4Leithd=1.5,
>  viscA4GridMax=0.5,
>
> Recently I have noticed a little more grid scale noise than before but 
> it is hard
> to separate this from other modifications to code and model configuration
>
> Do I need to increase  viscA4GridMax by about 30%, as per Martin's email,
> to recover previous set up?
Dimitri,
looks like the changes in L4rdt also apply to viscA4GridMax.
But I'm not sure about those 30% of Martin: he was talking about L4, not 
L4rdt.
In fact, I'm not even sure that L4 is used in mom_cal_visc.F.
david




>
> Thanks, Dimitris
>
> On Jul 31, 2009, at 1:02 PM, David Ferreira wrote:
>
>> Martin,
>> I put a note in the tag-index about the L4rdt fix !
>> Surely, everybody reads it regularly...
>> Anyway, the viscosity at the corner points were 4 times those at the
>> center points, so
>> the "effective" viscosity was larger than intended. And indeed, with the
>> new code, it will
>> probably be necessary to pump up a bit viscA4grid.
>> That said, I don't think that L4 was changed by the code modification,
>> only L4rdt.
>> Are you sure there is not something else going on ?
>> Cheers,
>> david
>
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