[MITgcm-devel] new salt_plume param?

[Gael Forget]

Hi An. Sounds great. Gael

On May 27, 2011, at 2:05 PM, An T Nguyen wrote:

> hi Gael,
> 
> Let's discuss about this when I come in on Monday? I made some more adjustments in a version which we did not check in yet that might also address some of the things you wanted to do. -An
> 
> On 5/27/11 7:58 AM, Gael Forget wrote:
>> Hi Dimitris,
>> 
>> I am glad that you sympathize with the idea.
>> 
>> I appreciate the capability of turning off pkg/salt_plume by setting
>> useSALT_PLUME=.TRUE. and PlumeMethod=5. And, in the same
>> logic, I see that I could modulate the intensity of saltplumeFlux by
>> computing weighted averages of PlumeMethod=5 and the others.
>> 
>> But my suggested code would readily do this for any of the available
>> PlumeMethod's, at the expense of one code line.
>> 
>> I don't see why we would want to make it more complicated than that.
>> I don't see either why applying the proposed factor to saltplumeFlux
>> in seaice_growth would be an inappropriate place, since this is
>> precisely where saltplumeFlux is set. Seems transparent to me.
>> 
>> Anyway, I can leave this out of the main trunk if you prefer.
>> 
>> Cheers,
>> Gael
>> 
>> On May 27, 2011, at 12:20 AM, Menemenlis, Dimitris (3248) wrote:
>> 
>>> Gael, if I understand your suggestion correctly, you are trying to add a redistribution
>>> that would leave (1-SaltPlumeIntensity) in the surface level, in addition to whatever
>>> is left there by the particular "PlumeMethod" that has been selected.
>>> I think this is a good suggestion but a cleaner way to implement would be to
>>> add one or more PlumeMethod distributions to salt_plume_frac.F in addition
>>> to the ones that are already there.  For example, the current PlumeMethod=5
>>> is  equivalent to your SaltPlumeIntensity=0 and the other PlumeMethod
>>> distributions all leave behind some percentage of salt in the surface level.
>>> 
>>> Another argument against adding a constant SaltPlumeIntensity in seaice_growth.F
>>> is that conceptually this parameter should not be everywhere constant.  Instead it
>>> should probably be modulated by the fraction of lateral vs bottom freezing occurring
>>> in each grid cell at a particular moment in the integration.  Again, salt_plume_frac.F
>>> would be a better location to carry out such calculation rather than seaice_growth.F
>>> 
>>> Dimitris Menemenlis
>>> 
>>> On May 26, 2011, at 12:55 PM, Gael Forget wrote:
>>> 
>>>> Hi An and co,
>>>> 
>>>> my understanding is that the current set of parameters
>>>> allows various redistribution profiles shape and reach.
>>>> 
>>>> I was surprised not to find one to tune, not the shape,
>>>> but the very intensity of the parameterization.  Did I miss it?
>>>> 
>>>> In my tests I added the following, which seems to provide for an
>>>> easy tuning of the salt plume parameterization strength.
>>>> I thought it could be of interest to other users. So, do you mind if
>>>> I introduce a SaltPlumeEfficiency factor in seaice_growth.F to do
>>>>            saltPlumeFlux(I,J,bi,bj)=
>>>>    &             HEFFM(I,J,bi,bj)/SEAICE_deltaTtherm
>>>>    &             *(1-SIsalFRAC)*salt(I,j,kSurface,bi,bj)
>>>>    &             *tmpscal1*SEAICE_rhoIce
>>>>    &             *SaltPlumeIntensity
>>>> It would range from 0 to 1, and have a default of 1. I believe the
>>>> above snippet would be a correct way to do this. Isn't it?
>>>> 
>>>> Cheers,
>>>> Gael
>>>> 
>>>> 
>>>> 
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> -- 
> An T Nguyen, Ph.D.<atnguyen at mit.edu>
> MIT Bldg 54-1410
> 77 Massachusetts Ave, Cambridge MA 02139, USA
> Phone: 617 253 2443; Fax: 617 253 4464
> 
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