Dear Heinke
> And I like to ask Jonathan why he changed his mind.
> see:
> http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2007/001654.html
> 'Many of them have definitions which require the combination of the
> specification of a physical quantity with the value of a parameter,
> where the
> parameter appears to Alison and me to be most naturally expressed as a
> coordinate variable or scalar coordinate variable in CF. This isn't a new
> kind of situation, but it is an issue worth thinking about.'
>
> 'We decided on the CF approach because it is more general and it reduces the
> size of the standard name table by "factorising" the information. We could
> have taken this approach further and made the standard name table more
> hierarchical.'
That discussion was about the extreme stats, and my comment then refers to
continuous numerical variables. We don't put them in standard names e.g. we
are not proposing a standard name for the number of days when the temperature
exceeds 30degC, with 30degC appearing explicitly in the standard name. That
can be put in a coordinate variable instead.
Chemical species are not continuously variable parameters. That makes some
difference and it's why I gave a different view. But the discussion has been
reopened because, while not continuously variable, there might still be a
very large number of them. Hence I am agreeing with you that we could consider
instead putting them in a coordinate variable.
> Is the decision made to list each chemically related
> standard name all explicitly in the CF standard name list ?
This is not clear to me either. Recent emails seem to be in favour of still
putting them explicitly in the standard name i.e. *not* using a coordinate
variable, in order to guarantee that only meaningful combinations are included.
But I think it could be done either way.
Best wishes
Jonathan
Received on Thu Oct 30 2008 - 12:01:51 GMT
