[MITgcm-devel] non-legacy seaice

[Martin Losch]

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

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