[MITgcm-devel] non-legacy seaice

[Jean-Michel Campin]

Hi Gael,

Thanks for your "side notes", but I am not sure this is crucial regarding
the problem of unrealistic low SST, so I've started a new thread.

Cheers,
Jean-Michel

On Tue, Jan 31, 2012 at 09:27:29AM -0500, Gael Forget wrote:
> 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
> >>> 
> >>> 
> >>> 
> >>> 
> >>> 
> >>> 
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> >> 
> >> 
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