[MITgcm-devel] sea ice clean up this week

[Gael Forget]

Martin,

you are right I messed up the untested case. Thanks for catching it early.

The correct code (in the current state of affairs) would be
           elseif ( (SEAICEturbFluxFormula.EQ.4).AND.
     &        (AREApreTH(I,J) .GT. 0. _d 0) ) then
              MixedLayerTurbulenceFactor = ONE/MCPHEE_TAPER_FAC
Correct. May be now that we can switch on this case through a run time parameter
we should have the second mcphee case tested in a sub-exp of Ian's 1D exp.

Also I went half way there. My intention was to ultimately have the MCPHEE_TAPER_FAC param
become 11.5/12.5 (in readparms or initfixed normally) and not be 12.5. In growth this would give
           if ( (SEAICEturbFluxFormula.EQ.3).AND.
     &        (AREApreTH(I,J) .GT. 0. _d 0) ) then
              MixedLayerTurbulenceFactor = ONE - MCPHEE_TAPER_FAC*AREApreTH(I,J)
           elseif ( (SEAICEturbFluxFormula.EQ.4).AND.
     &        (AREApreTH(I,J) .GT. 0. _d 0) ) then
              MixedLayerTurbulenceFactor = ONE - MCPHEE_TAPER_FAC
Correct? This makes the tapering strategy clearer and has no division in it.

I have a check-in planned today mostly for diags, checks and summary.
I can do the above at the same time if this works for you. Does it?

Cheers,
Gael

ps : I still need to send you guys a summary+guidelines regarding fridays' changes...


On Feb 13, 2012, at 6:03 AM, Martin Losch wrote:

> Gael,
> 
> I have not been able to understand the new MCPHEE+GRADIENT_MIXED_LAYER_* logic.
> 
> - MCPHEE_TAPER_FAC = 12.5
> - seaice_init_fixed for SEAICEturbFluxFormula.EQ.3 or 4
>        SEAICE_availHeatFrac= MCPHEE_TAPER_FAC * more constants
>        SEAICE_availHeatFracFrz=ZERO
> - seaice_growth: 
>          elseif ( (SEAICEturbFluxFormula.EQ.4).AND.(AREApreTH(I,J) .LE. 0. _d 0) ) then
>              MixedLayerTurbulenceFactor = MCPHEE_TAPER_FAC
>           else
>              [ ... ]
> 
> This looks to me as if you have MCPHEE_TAPER_FAC^2. It should be MixedLayerTurbulenceFactor=1 in the above case as the default (the final else) 1/MCPHEE_TAPER_FAC. So I suggest that we remove MCPHEE_TAPER_FAC in seaice_init_fixed:
>        SEAICE_availHeatFrac= STANTON_NUMBER * 
>     &    USTAR_BASE / dRf(kSurface) * SEAICE_deltaTtherm
> and adjust seaice_growth accordingly. This also avoids a division in a loop. If you don't object. I'll do it. (This options is not tested, because these changes do not change any results).
> 
> M.
> 
> 
> On Feb 9, 2012, at 8:16 PM, Gael Forget wrote:
> 
>> Dear all,
>> 
>> below is (A) a summary of the last two day clean-up steps (cosmetic changes) 
>> and (B) what it means for known users (based on Patrick's table; attached).
>> In case you follow testreport, you already know that the modifs have not 
>> changed anything to results. Notice : there is more clean-up coming in the 
>> next couple days, so you may want to wait until doing an update, up to you.
>> 
>> Cheers,
>> Gael
>> 
>> (A) 
>> 
>> retired CPPs : 
>> 	MCPHEE_OCEAN_ICE_HEAT_FLUX
>> 	GRADIENT_MIXED_LAYER_TURBULENCE_FACTOR
>> 	SEAICE_OCN_MELT_ACT_ON_AREA, SEAICE_DO_OPEN_WATER_GROWTH
>> 	SEAICE_DO_OPEN_WATER_MELT, FENTY_AREA_EXPANSION_CONTRACTION
>> 
>> added run time params. I include a copy of the doc in SEAICE_PARAMS.h and 
>> tried to trace back where the various options came from (text in parentheses).
>> 	SEAICE_doOpenWaterGrowth, SEAICE_doOpenWaterMelt
>> 		T/F 	just like the old CPP versions
>> 		T	use open water heat flux directly to grow ice	(Ian way)
>> 		F 	cool ocean, and grow later if needed		(Zhang way)
>> 	SEAICEturbFluxFormula :: selects formula for ocean-ice turbulent flux
>> 		1=direct spec. of SEAICE_availHeatFrac/Frz		(Dimitri/Ian way)
>> 		2=spec. via SEAICE_gamma_t/_frz				(Martin/Ian way)
>> 		3=McPhee with linear tapering					(Ian latest way)
>> 		4=McPhee with step function					(Ian other latest way)
>> 	SEAICE_areaLossFormula :: selects formula for ice cover loss from melt
>> 		1=from all but only melt conributions by ATM and OCN	(Ian way)
>> 		2=from net melt-growth>0 by ATM and OCN		(Gael/Ian way)
>> 		3=from predicted melt by ATM					(Zhang way)
>> 	SEAICE_areaGainFormula :: selects formula for ice cover gain from open water growth
>> 		1=from growth by ATM						(Ian way)
>> 		2=from predicted growth by ATM				(Zhang way)
>> 
>> as a side note, I put stops in seaice_check.F	 for combinaisons
>> that are obviously problematic. Tyipically, if you do NOT use  
>> SEAICE_doOpenWaterGrowth you need to use the Zhang way
>> for SEAICE_areaLossFormula (3) and SEAICE_areaGainFormula (2),
>> and this is the only case allowed with SEAICE_GROWTH_LEGACY.
>> 
>> (B) 
>> 
>> You should double check, but based on Patrick's table, 
>> here is what you will need to add to your namelists : 
>> 
>> Martin : 	in SEAICE_GROWTH_LEGACY case you should be all set. Otherwise
>> 		if TRUE SEAICE_doOpenWaterGrowth then SEAICE_areaLossFormula = 2
>> 		if FALSE SEAICE_doOpenWaterGrowth then SEAICE_areaLossFormula = 3, SEAICE_areaGainFormula=2
>> 
>> Ian et al:	SEAICE_doOpenWaterMelt=.TRUE.
>> 		SEAICEturbFluxFormula=3
>> 		ps: def/undef SEAICE_OCN_MELT_ACT_ON_AREA was doing nothing 
>> 		      since FENTY_AREA_EXPANSION_CONTRACTION was def.
>> 
>> Me : TBD.
>> 
>> 
>> <seaice_whodoeswhat_3.pptx>
>> 
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