[MITgcm-support] seaice setup for idealized ice leads experiment

[Martin Losch]

Mehmet,

as a dirty hack, you could set 
SEAICE_boltzmann=0. in seaice_readparms.F
(or maybe even stefanBolztmann=0. in EXF_CONSTANTS.h) to have no upward lw radiation.

Martin

On Sep 17, 2012, at 11:57 AM, Martin Losch wrote:

> Mehmet,
> 
> I think you need to specify some radiation fields, at least non-zero downward longwave radiation to balance the upward radiation by the ice (stefanBoltzmann*Tice**4). I think (without checking your set up very closely) you see ice formation because of this strong imbalance.
> 
> Martin
> 
> On Sep 14, 2012, at 9:51 PM, Mehmet Ilicak wrote:
> 
>> 
>> Hi all,
>> 
>> I'm trying to perform some idealized ice leads experiments using mitgcm with seaice pkg in a nonhydrostatic setup.
>> I am very new to ice modelling, so I decided to seek for help.
>> 
>> The domain is 10x10km periodic.
>> Initial condition of temperature is uniform and -2C in the ocean. For salinity upper 50m 32psu and below that it is 32.2psu.
>> T/S advection sheme is 33.
>> It is linear equation of state. The freezing temperature is also -2C.
>> 
>> There is initial ice thickness (2 meter) everywhere except 1x1 km in the middle of the domain. In that area I put random ice thickness order of 2.5 cm.
>> I also add snow thickness (20cm) on top of the ice to increase insulation.
>> 
>> I am using exf package to force the ocean-ice model with air temperature. The air temperature is uniform and 253K (-20C) in the file.
>> The rest of the forcing fields are not defined.
>> 
>> This setup is very similar to Matsumura and Hasumi (2006).
>> 
>> What I was expecting is that in the lead opening, there will be ice formation because of the cold air. And when the ice forms, it rejects salt, so the water will get denser and sink in that 1x1 km area.
>> But I've seen some additional salt rejection everywhere under ice.
>> I've attached a picture of salinity x-z section. (See the top of the domain, you can see saltier water everywhere)
>> I don't understand why there is more salty water on the surface far away from the ice leads.
>> In addition, sea ice thickness is increasing everywhere.
>> 
>> I think, there might be something wrong in my setup.
>> The paper that I cite does not mention this salinity anomaly.
>> 
>> I changed the ice conductivity from 2 to 0.02. It reduces the salt anomaly under ice far from ice leads but it also reduces the salt rejection in the ice leads.
>> I increase initial sea ice thickness around 10 meter, but still I saw the anomaly and I thought ice thickness is not realistic.
>> Finally I changed the air temperature to -2C everywhere except the ice-leads area. But the salt anomaly is still there.
>> 
>> I appreciate any suggestion.
>> 
>> Best,
>> Mehmet
>> 
>> 
>> 
>> Here is my data.seaice;
>> 
>> &SEAICE_PARM01
>> #- seaice dynamics params:
>> LSR_ERROR          = 1.E-12,
>> SEAICE_no_slip     = .TRUE.,
>> SEAICE_drag        = 0.001,
>> ICE2WATR           = 0.92D0,
>> HeffFile           = 'HEFF.init',
>> HsnowFile          = 'HSNOW.init',
>> SEAICE_salt0       = 10.0,
>> #- constant seawater freezing point:
>> SEAICE_tempFrz0    = -2.0,
>> SEAICE_saltFrac    = 0.3,
>> SEAICE_dTempFrz_dS = 0.0,
>> #  MIN_ATEMP          = -40.,
>> #  MIN_TICE           = -40.,
>> SEAICEadvScheme    = 7,
>> # for adjoint simulations you will need
>> # SEAICEadvScheme    = 30,
>> #- seaice thermodyn params:
>> SEAICE_multDim     = 1,
>> SEAICE_wetAlbTemp  = 0.0,
>> # this value should be default for the McPhee parameterization
>> SEAICE_mcPheeTaper = 0.92,
>> #- seaice I/O params:
>> SEAICEwriteState   = .TRUE.,
>> &
>> 
>> &SEAICE_PARM03
>> SItrNumInUse       = 1,
>> SItrName(1)        = 'salinity',
>> SItrFromOceanFrac(1) = 0.3,
>> &
>> 
>> 
>> Ref:
>> Brine-Driven Eddies under Sea Ice Leads and Their Impact on the Arctic Ocean
>> Mixed Layer . YOSHIMASA MATSUMURA AND HIROYASU HASUMI 2006
>> <salt_xzsection.png>_______________________________________________
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> 
> 
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