Default local_mixing_frac value

[milicak]

Hi,

I am trying to export CVmix into our climate model NorESM similar to MOM6.
While I was coding tidal mixing, I saw this line
call cvmix_put_tidal("local_mixing_frac", 3, CVmix_tidal_params_user)

Normally local_mixing_frac default value should be 1/3 in the tidal mixing parameterizations.
Is there a reason why the default value is 3?

Thanks in advance,
Best,
Mehmet

[mnlevy1981]

Thank you for pointing this out! You are correct, according to Simmons, et al. (2004) the proper default value is 1/3. In fact, the stand-alone tidal mixing driver provided as an example with CVMix sets this mixing fraction to 0.33, so I'm not sure how we ended up with the wrong default value.

POP also sets this value to 0.33 in its namelist and then uses this namelist value when calling cvmix_init_tidal()... I do want to check in with the MOM group to make sure they are also overriding this incorrect default (or perhaps they aren't using tidal mixing at all?), but you should definitely not use this default value.

Thanks again for bringing this up.

[milicak]

Thanks for the quick answer
I think MOM6, GFDL group is using 0.33 in their code (I can check that), but I am not %100 sure about the MOM6, NCAR setup.

[gustavo-marques]

Thanks for catching that, Mehmet.
Mike, the default value for this parameter in MOM6 is 0.33 (see here) and that is what we have been using.
Thanks!

[StephenGriffies]

GFDL does not use CVMix att. Thanks for checking. I suggest changing the CVMix default to the documented 0.33 value.