[MITgcm-devel] description of seaice parameters

[Jinlun Zhang]

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