[MITgcm-devel] description of seaice parameters

[Martin Losch]

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.
>>
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>
>
> -- 
>
> 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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