[MITgcm-devel] ICE workshop - recap and homework!

[Gael Forget]

Martin et al.,
forget most of my previous email. I re-copy below the rest of my 
reply. The stop strategy apparently makes no sense 
to anyone but me. So I wiped out the stops for
> MCPHEE_OCEAN_ICE_HEAT_FLUX

> GRADIENT_MIXED_LAYER_TURBULENCE_FACTOR
> SEAICE_VARIABLE_FREEZING_POINT
I left a simple comment to STDERR that we will remove later.
Please remove the CPPs in the upcoming "packaged set of 
SEAICE_OPTIONS.h, data.seaice, and data.diagnostics".

>> -----------------------------------------------------------------------------------------
>> old default : SEAICE_tempFrz0 = -1.96, SEAICE_dTempFrz_dS = 0.
>> new default : SEAICE_tempFrz0 = 0.0901, SEAICE_dTempFrz_dS = -0.0575
>> ?? do we have a precise reference for 0.0901 + S * SEAICE_dTempFrz_dS ??
> Good question. The unesco eos (Fofonoff and Millard 1983) says this:
> a0 = -0.0575;
> a1 = 1.710523e-3;
> a2 = -2.154996e-4;
> b  = -7.53e-4;
> fp = (a0.*S + a1.*S.*sqrt(S) + a2.*S.^2 + b.*P) / 1.00024;
> 
> Holland and Jenkins (1999) cite
> Millero, F. J. (1978): Annex 6: Freezing point of seawater. Eighth Report of the Joints Panel of Oceanographic Tables and Standards, UNESCO Technical Papers in Marie Science, 31 pp.
> for a linear formula (their eq (1)): Tf=a*S+b+c*p, with a=-5.73e-2degC/psu, b=9.39e-2degC, c=7.53e-8 degC/Pa.
> 
> So that's slightly different (and I actually use a=-5.75e2, b=9.01e-2, c=7.61e-8 in shelfice_thermodynamics.F), what does that tell us?
Thanks for looking this up. My guess is that we got a linear version 
of Fofonoff and Millard 1983 then (SEAICE_dTempFrz_dS= -0.0575).
Shall we add this ref next to defaults in readparams ?

>> def/undef SEAICE_MULTICATEGORY : no change to default. So use CPP as before. ...
>> But added run time switch : set SEAICE_multDim to 1 or 7, regardless of CPP. It is assumed 
>> that user provide pickup accordingly, as before. Pickup code will likely need consolidation.
> After the pickup code is sorted out this CPP-flag should also be retired, right?
If somebody else wants to take care of the pickups that's great ;)
As far as the CPP I vote for retiring the bunch of old stuff late May/early June.

>> old def/undef MCPHEE_OCEAN_ICE_HEAT_FLUX & GRADIENT_MIXED_LAYER_TURBULENCE_FACTOR .... 
> Just to make sure: If I want to reproduce the old configuration of
> #define MCPHEE_OCEAN_ICE_HEAT_FLUX
> #define GRADIENT_MIXED_LAYER_TURBULENCE_FACTOR
> I have to set
> SEAICE_mcPheePiston = 0.000875, (this is default and need not be set)
> SEAICE_frazilFrac=0., (this is not default)
> SEAICE_mcPheeTaper=0.92, (this is not default)
> SEAICE_mcPheeStepFunc=.false., (this is default and implies the linear function only if mcPheeTaper .ne. 0)
Perfectly correct.

>> ?? do we have a precise reference for 0.000875 and 0.92 ??
Ian can you help us with that one?

> For the baseline experiments we agreed on frazilFrac = 1., so that means for the baseline data.seaice we now have:
>>> cat data.seaice
> &SEAICE_PARM01
> # SEAICEheatConsFix  = .TRUE.,
> SEAICE_no_slip     = .TRUE.,
> SEAICEadvScheme    = 7,
> # for adjoint simulations you will need
> # SEAICEadvScheme    = 30,
> SEAICE_drag        = 0.001,
> SEAICE_wetAlbTemp  = 0.0,
> SIsal0             = 4.0,
> # this is a temporary set of parameters to allow super-cooled water
> # to turn into sea-ice until the interior freezing/frazil capabilities have
> # matured
> SEAICE_mcPheeTaper=0.92,
> # Depending on vertical resolution this angle should have a value
> # > 0 (e.g., 25deg for drF(1)=10m,)
> # SEAICE_waterTurnAngle = 0.0,
> &
> Please confirm, and once confirmed, we can make another packaged set of SEAICE_OPTIONS.h, data.seaice, and data.diagnostics
I confirm. 

Cheers,
Gael