[MITgcm-devel] non-legacy seaice

[Gael Forget]

Martin et al,
> 


two side notes. 

First, I am not sure about the details of the SEAICE_SOLVE4TEMP_LEGACY switch.
To my knowledge the differences there are minor and that switch is largely independent of 
the SEAICE_GROWTH_LEGACY switch. At least it was until last summer's sublimation changes. 
Thanks Jean Michel for taking charge of seaice_solve4temp.F.

Second, I believe SEAICE_HEAT_CONSERV_FIX is needed as soon you dont use temp_EvPrRn=0. 
In this case all of empmr, which after seaice_growth includes freeze/melt water fluxes, is treated as having 
a temperature of theta(i,j,1,bi,bj), whereas pkg/seaice implies that the ice energy is constant (-Lf at 0C typically). 
The issue came up when I failed to close the ocean+ice budgets. Basically, if you freeze and then melt for 
different theta values, I think the coupled ocean+ice system looses heat without SEAICE_HEAT_CONSERV_FIX. 
Note that we only checked ocean budgets and ice budgets separately last spring. 

Cheers,
Gael

On Jan 31, 2012, at 8:15 AM, Martin Losch wrote:

> Hi Ian,
> 
> I tried with your option combination, and the problem does not go away (THETA=-37degC). What do you suggest?
> 
> Martin
> 
> On Jan 30, 2012, at 6:27 PM, Fenty, Ian G (3248-Affiliate) wrote:
> 
>> 
>> On Jan 30, 2012, at 8:04 AM, Martin Losch wrote:
>> 
>>> Dear sea-ice modelers,
>>> 
>>> just out of curiosity I turned on the non-legacy seaice code (SEAICE_GROWTH_LEGACY undefine and SEAICE_SOLVE4TEMP_LEGACY undefined and set some other flags that go along with it, see below). To further my boldness, I also turned on:
>>> #define MCPHEE_OCEAN_ICE_HEAT_FLUX
>>> #define GRADIENT_MIXED_LAYER_TURBULENCE_FACTOR
>> 
>> Martin,
>> The non-legacy compile time sea ice flags are not independent.  The set of flags for which I have confidence is:
>> 
>> #undef SEAICE_GROWTH_LEGACY
>> #undef SEAICE_SOLVE4TEMP_LEGACY
>> 
>> #define MCPHEE_OCEAN_ICE_HEAT_FLUX
>> #define GRADIENT_MIXED_LAYER_TURBULENCE_FACTOR
>> #define SEAICE_DO_OPEN_WATER_GROWTH
>> #define SEAICE_DO_OPEN_WATER_MELT
>> #define FENTY_AREA_EXPANSION_CONTRACTION
>> #define SEAICE_ADD_SUBLIMATION_TO_FWBUDGET
>> 
>> As for the recent SEAICE_HEAT_CONSERV_FIX, I can say nothing because there was no documentation about it in devel (as far as I noticed) and minimal documentation in the code.  Perhaps it is unnecessary when not coupling with an active atmosphere?    
>> 
>> Anyhow, with that above set of flags I can help diagnose any problems (e.g., with unexpectedly cold surface temperatures) and nonzero HEFF over land.  Please rerun the simulation if you can!
>> 
>> -Ian
>> 
>> 
>>> The solutions that I get for an Arctic domain are comparable but different. The non-legacy code gives generally thicker ice in the interior, which I think is generally good, as the legacy code tends to produce ice that's on the "thin side" compared to other solutions.
>>> 
>>> However (appart from the fact that there was HEFF~=0 over land), I get very cold surface temperatures (down to -21degC) in some areas (Lena Delta), interesting this starts in June/July when ice should be melting. That's clearly not very physical and I am wondering if others have observed this behavior. Is there a solution to this? Before I try it myself, is it connected to the 
>>> #define MCPHEE_OCEAN_ICE_HEAT_FLUX
>>> #define GRADIENT_MIXED_LAYER_TURBULENCE_FACTOR
>>> flags? (Likely, isn't it?) Or  SEAICE_OCN_MELT_ACT_ON_AREA?
>>> 
>>> Your experience with this is appreciated ...
>>> 
>>> Martin
>>> 
>>> PS. Here are the relevant flags:
>>> C--   make conservation of freshwater complete
>>> #undef SEAICE_ADD_SUBLIMATION_TO_FWBUDGET
>>> 
>>> C--   Use the Old version of seaice_growth (close to cvs version 1.70)
>>> C     otherwise, use the merged version (with some of Ian Fenty s code)
>>> #undef SEAICE_GROWTH_LEGACY
>>> 
>>> C--   options only available in the merged version (from Ian Fenty s code)
>>> #ifndef SEAICE_GROWTH_LEGACY
>>> C-    to ensure heat conservation in the coupled ocean-seaice system
>>> #define SEAICE_HEAT_CONSERV_FIX
>>> C-    to switch on/off open-water freezing contribution to thickness tendency:
>>> # define SEAICE_DO_OPEN_WATER_GROWTH
>>> C-    ifdef SEAICE_DO_OPEN_WATER_GROWTH then define SEAICE_DO_OPEN_WATER_MELT
>>> C     to also allow open-water air-sea heat fluxes melt ice
>>> # undef SEAICE_DO_OPEN_WATER_MELT
>>> C-    to switch on/off ocean heat contribution to seaice cover reduction:
>>> # define SEAICE_OCN_MELT_ACT_ON_AREA
>>> C-    to preclude infinitesimal ice concentrations:
>>> # undef ALLOW_PRECLUDE_INFINITESIMAL_AREA
>>> #endif
>>> 
>>> C-    to use the MCPhee formula in computing ocean/ice fluxes
>>> #define MCPHEE_OCEAN_ICE_HEAT_FLUX
>>> #define GRADIENT_MIXED_LAYER_TURBULENCE_FACTOR
>>> 
>>> C--   Use the Old version of seaice_solve4temp (formerly seaice_budget_ice)
>>> C     otherwise, use Ian Fenty s version
>>> #undef SEAICE_SOLVE4TEMP_LEGACY
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> MITgcm-devel mailing list
>>> MITgcm-devel at mitgcm.org
>>> http://mitgcm.org/mailman/listinfo/mitgcm-devel
>> 
>> 
>> _______________________________________________
>> MITgcm-devel mailing list
>> MITgcm-devel at mitgcm.org
>> http://mitgcm.org/mailman/listinfo/mitgcm-devel
> 
> 
> _______________________________________________
> MITgcm-devel mailing list
> MITgcm-devel at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-devel