[geotk] nature.SeaWater.density

[Martin Desruisseaux]

Hello John

Le 18/05/10 18:22, Jonathan Blower a écrit :
> I was very interested to stumble upon the nature.SeaWater class, which
> neatly fills a need I have to calculate sea water density.  Which
> formula does this class use in the density(S,T,P) method?

This class is a port of Fortran code used in Fisheries and Oceans Canada 
"Maurice Lamontagne" institute. The Fortran code is itself an implementation of 
the formulas published by Unesco:

     International oceanographic tables, volume 4.
     Unesco technical papers in marine science #40 (1987).

I complete them with the formulas specific to high salinities:

     Alain Poisson, M.H. Gashoumi and Selim Morcos.
     Salinity and density of seawater: table for high salinities (42 to 50).
     Unesco technical papers in marine science #62 (1991).

Actually the references are listed there:

http://www.geotoolkit.org/apidocs/org/geotoolkit/nature/package-summary.html#package_description

I have compared the output from the Java port with the output of the original 
Fortran program, and the result was close to identical for every values I have 
tested. Consequently I think that the density(S,T,P) function is reliable. The 
only doubt I had is about whatever the pressure argument include the atmospheric 
pressure or not (the UNESCO paper was not clear about that), but by examination 
of input/putput values I think it does not.

	Regards

		Martin