[Fwd: RE: [MITgcm-support] grid-scale noise in 1/4-deg model]

[Dimitris Menemenlis]

Alistair, thanks for the tip.

With COSINEMETH_III and ISOTROPIC_COS_SCALING properly set, I can
increase biharmonic friction and viscosity by a factor of 30.  Results
in the attached figure compare Kuroshio and West African coast regions
for 1e10 and for 2e11 m^4/s.

To do this however I have to use cosPower=4 not cosPower=2.  Was that a
typo in your message yesterday?

For reference, here is table of experiments.  The grid is isotropic,
80S-80N, 1/4-deg grid-spacing at the Equator.  Time step is 480 s.

cosPower     visca4,diffk4      result
====================================
2              5e10                  OK
2              1e11                  bombs
3              1e11                  OK
3              2e11                  bombs
4              3e11                  OK
4              4e11                  bombs

Please confirm that using cosPower=4 for an isotropic grid is OK.

D.

-- 
Dimitris Menemenlis <menemenlis at jpl.nasa.gov>
Jet Propulsion Lab, California Insitute of Technology
MS 300-323, 4800 Oak Grove Dr, Pasadena CA 91109-8099
tel: 818-354-1656;  fax: 818-393-6720
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