[MITgcm-devel] description of seaice parameters

[Jinlun Zhang]

Thanks for the info, Martin. I am curious about changes Markus made for 
the dynamics solver. Perhaps some changes we could adopt to mitgcm. Do 
you know any way to access the ice code? I couldn't see it from AWI web 
site.

Jinlun

Martin Losch wrote:

> Hi Jinlun,
>
> here's what I found out about the ice-dynamics of the AWI seaice model:
> viscous-plastic with the Hibler numerics + some essential refinements
> that Markus (Harder+Lemke, 1994, AGU Geophysical Monograph 85) did.
>
> That's it,
> Martin
>
> On Sep 13, 2005, at 12:51 AM, Jinlun Zhang wrote:
>
>> Hi Martin,
>>
>> Good observations. When I wrote the seaice model for MITgcm, I tried 
>> to keep Hibler original as much as possible. For example, -1.96 degC 
>> and SEAICE_strength=2.75e4 are  Hibler original. The thermodynamics 
>> is also from Hibler original. However, ice dynamics is from Zhang and 
>> Hibler (1997), although all the names of the variables are 
>> deliberately kept the same. The Zhang and Hibler dynamics method is 
>> fast, and has been adapted for parallel computing, as in MITgcm. This 
>> dynamics code has been sent out to some European researchers, but who 
>> knows how many groups, if any, are using it. Would be interested to 
>> know what ice dynamics AWI is using.
>>
>> Jinlun
>>
>> Martin Losch wrote:
>>
>>> Hi Dimitry,
>>>
>>> I have talked to one of our sea-ice specialists about the default 
>>> parameter values in seaice_readparms.F. There are a few small 
>>> differences in what he uses. The biggest difference is in 
>>> SEAICE_freeze, which is -1.96degC in seaice_readparms.F, but 
>>> -1.86degC in his code. Maybe still another reason for the thin ice 
>>> around Antarctica and the large erroneous polynyas in the high-res 
>>> cubed sphere experiments. Also he uses a smaller value of 
>>> pstart=1.5e4 (instead of SEAICE_strength=2.75e4 in 
>>> seaice_readparms.F). Only FYI.
>>>
>>> However, we found that the parameters 
>>> SEAICE_sensHeat/latentWater/latentIce are not really the 
>>> coefficients as described in SEAICE_READPARMS.h but
>>> (density of air)*(heat capacity of air/latent heat of water/latent 
>>> heat of ice)*(transfer coefficient)
>>>
>>> At least, that's what we found by comparing the code and default 
>>> values. If you want me to do it I'll change the description in 
>>> SEAICE_READPARAMS.h to reflect this, so that future seaice-novices 
>>> do not stumble over this?
>>>
>>> Martin
>>>
>>> PS. It is funny that the seaice code and the code that is used at 
>>> AWI are very similar (variable names etc.). It is obvious that both 
>>> codes are derivatives from the same (original Hibler?) code.
>>>
>>> _______________________________________________
>>> MITgcm-devel mailing list
>>> MITgcm-devel at mitgcm.org
>>> http://mitgcm.org/mailman/listinfo/mitgcm-devel
>>
>>
>>
>> -- 
>>
>> Jinlun Zhang
>> Polar Science Center, Applied Physics Laboratory
>> University of Washington, 1013 NE 40th St, Seattle, WA 98105-6698
>>
>> Phone: (206)-543-5569    Fax:    (206)-616-3142
>>
>> zhang at apl.washington.edu
>> http://psc.apl.washington.edu/IDAO
>>
>>
>>
>>
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>
>
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