[MITgcm-devel] non-legacy seaice

[Gael Forget]

Hi Martin,

it is nice to see somebody else than me putting those the various evolution branch codes through sensitivity tests. 
Running such experiments with more than one setup is needed before we can make informed decisions 
about the evolution branch defaults. I was not planning on putting more work in seaice_growth.F right now. 
But I guess, since there is some new momentum, now is the time...

With regard to runaway temperatures, here are my comments. First, as Jean Michel 
previously mentioned, Jeff and I have seen that using areamax<1 favors
runaway temperatures. In my set-up, the problem disappeared by setting areamax to 1. 
	You are not using areamax<1 are you?
Second, MCPHEE_OCEAN_ICE_HEAT_FLUX is likely to increase that issue. Indeed 
theta<freezing means the ocean heat deficit is not used to freeze (see line 885) unlike
what is done in the other options. 
	Have you tried with MCPHEE_OCEAN_ICE_HEAT_FLUX false?

Cheers,
Gael

ps : sorry Jean Michel I did not reply faster. 

On Jan 31, 2012, at 7:36 AM, Martin Losch wrote:

> Hi Jean-Michel and others,
> 
> thanks for your comments. I did not plan on using the non-legacy code "by default", I just thought that it is interesting that just turning it one is far from safe.
> 
> I'll try with Ian's options. Why isn't this combination the default in pkg/seaice/SEAICE_OPTIONS.h?
> 
> M.
> 
> On Jan 31, 2012, at 6:56 AM, Jean-Michel Campin wrote:
> 
>> Hi Martin,
>> 
>> Just a short comment: if Gael does not want to answer, you can
>> always return to SEAICE_GROWTH_LEGACY version, or, as an other
>> alternative, switch to pkg/thsice thermodynamics as Jeff did.
>> 
>> Cheers,
>> Jean-Michel
>> 
>> On Mon, Jan 30, 2012 at 12:52:13PM -0500, Jean-Michel Campin wrote:
>>> Hi Martin,
>>> 
>>> I heard form 2 other users (Jeff Scott and Gael, but both with
>>> similar options & params) a similar issue regarding unrealistic 
>>> surface temp.
>>> So, I think it's a more general problem that just our set-up.
>>> 
>>> Cheers,
>>> Jean-Michel
>>> 
>>> On Mon, Jan 30, 2012 at 05:04:48PM +0100, 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
>>>> 
>>>> 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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