[MITgcm-support] Re: eosType!

[Martin Losch]

Hi Van Thinh,
has anybody answered your EOS question?
1. In general, don't use the UNESCO-EOS, it takes in-situ temperature 
as input, the model carries potential temperature.
2. For strict comparisons you could use a library routine such as that 
of the sea water library of Phil Morgan that implements the Gill-book 
formulae and set S=0. I think you neglected the pressure effects in 
your formula.

Martin

On Jul 26, 2005, at 4:02 PM, Ed Hill wrote:

>
> Hi Van Thinh,
>
> The following is the body of your email with the ~43MB of attachments
> removed since our email list has a 1MB upper limit.  In future, please
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> thanks,
> Ed
>
> ===
>
> Dear MITgcm-supporters!
>
> In order to simulate internal waves in a lake (salinity S=0), I used
> "eosType='UNESCO') for the equation of state. And I used the 
> diagnostics
> pkg to output the density, however I met some following problems:
>
> 1. I really don't know the ouputed results for density are based on
> which formula, because when I used the formula from Gill's book based 
> on
> UNESCO EOS to convert Temp. (T) output from the MITgcm model to the
> density (rho) for the pure water
>
> (rho=999.842594+6.793952*1.E-2*t-9.095290*1.E-3*t^2+1.001685*1.E-4*t^3
>     -1.120083*1.E-6*t^4+6.536332*1.E-9*t^5)
>
> Then I got a very diffenrent result in comparison with the density
> output from the MITgcm model. However, at the beginning to run the
> model, I used this formula to check with density output from the model
> at t=0 (RHOAnoma.0000000000.*), then I got the same result.
>
> I attach herewith 2 graphics of rho obtained from directly the model
> (rhoa24000.eps) and another obtained from converting of Temp to density
> by above formula (24000_in.eps).
>
> If anyone could know please help me to explain the reason why there
> are different when I used the same UNESCO EOS?
>
> Thanks so much!
>
> Van Thinh
>
>
> On Tue, 19 Jul 2005, Dimitris Menemenlis wrote:
>
>> Hi Van Thinh, I do not know exact cause of your error messages.
>> If I were in your situation I would try starting from scratch
>> with a new, clean copy of MITgcm, modify package.cong, then
>> genmake2, make depend, and make.
>>
>> Dimitris
>>
>
> -- 
> Edward H. Hill III, PhD
> office:  MIT Dept. of EAPS;  Rm 54-1424;  77 Massachusetts Ave.
>              Cambridge, MA 02139-4307
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