[CF-metadata] standard names for chemistry - MCM

[Philip J. Cameronsmith1]

Dear Stephen, Martin, et al.

I generally agree with Martin.

I will say, though, that the "two table approach" (or alternatively: "a 
two orthogonal vector approach") is particularly clean for chemistry.  In 
particular:

a) I cannot think of any "matrix elements" of quantity_for_species_X which 
would be undefined (although they may be negligibly small).

b) The list of species can then be easily be extended, even for 
applications that were not originally envisioned.

c) The units for the second vector (species) will all be identical.

d) If a "single vector" approach for CF standard names is retained, then 
when multiple intercomparison projects submit their "two vectors" there 
will be "gaps" in the combined set. For example, if project1 submits the 
matrix formed by the sets {quantities1} and {species1}, and project2 
submits the matrix formed by {quantities2} and {species2}, then there will 
be names that are undefined in the matrix formed by {quantities1 UNION 
quantities2} and {species1 UNION species2}.  Thus, with a "single vector" 
approach, subsequent projects will have to search the full standard name 
list for every "matrix element" to see whether it is defined, even if the 
quantity and specie are already recognized, and then submit those orphan 
names to the CF list.

e) The two vector approach will significantly reduce the burden of dealing 
with new standard name requests to this list (based on the arguments 
above).

In summary, I understand the desirability of maintaining a single "flat" 
list.  I also understand that allowing multiple attributes would cause a 
lot of problems in general (as Martin indicated).

However, is there a middle way, in which limited exceptions can be made in 
cases where the good strongly outweighs bad, eg could a limited exception 
be made for chemical names?

Yours truly,

      Philip

On Tue, 14 Oct 2008, Schultz, Martin wrote:

> Dear Stephen (Pascoe) and all,
>
>    thanks for your comment. You are certainly right that no one wants to 
> push 4500*physical parameters standard names. BUT: I am concerned that 
> your proposal to adopt CF (the "climate and forecasting" convention) to 
> the kinetics community might really cross a border. It is my 
> understanding that CF is tailored to Earth System Models, and they will 
> unlikely ever see 4500 chemical compounds (we are lucky if they include 
> more than 4 at this stage). Of course it might be an advantage if a 
> potential standard in the kinetics community would share many concepts 
> and terms with CF, but I don't think that CF itself is the right place 
> for this.
>
>    It seems to me like the real issue at hand is the decision whether or 
> not to include the compound name explicitely in the standard name or 
> not. Frankly, from my perspective, it would be the opposite from 
> Stephen's: if we have to go to other attributes, I fear that things 
> become so complicated that no one will use CF. Then again, there is some 
> virtue in the "two table approach" that Martin Suttie has brought into 
> the GRIB2 proposal. BUT, as things have developed in CF I fear this is a 
> fundamentally different approach. Why should there be two atributes for 
> chemistry but not for other quantities? Shouldn't the concept of 
> "change_of_X_due_to_Y" then also apply to, say temperature, salinity and 
> others?
>
> Best regards,
>
> Martin Schultz
>
> < Dr. Martin G. Schultz, ICG-2, Forschungszentrum Jülich  >
> < D-52425 Jülich, Germany                                 >
> < ph: +49 (0)2461 61 2831, fax: +49 (0)2461 61 8131       >
> < email: m.schultz at fz-juelich.de                          >
> < web: http:// www. fz-juelich.de/icg/icg-2/m_schultz       >
>
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------------------------------------------------------------------------
Dr Philip Cameron-Smith        Atmospheric, Earth, and Energy Division
pjc at llnl.gov                   Lawrence Livermore National Laboratory
+1 925 4236634                 7000 East Avenue, Livermore, CA94550, USA
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