Dear Martin/Jonathan,
This thread interests me greatly, but due to other pressures I have been unable to contribute, which is why I was getting so concerned at Martin pushing for a 'quick fix'.
There are two possibilities. First Frank's proposal for a common concept vocabulary is designed to do exactly what Jonathan is describing by mapping concepts (i.e. local codes) in Martin's namespace to multiple CF attributes. I think this is the best solution, but it may take a little time to become operational.
Secondly, I have an operational vocabulary server that could support a mapping between Martin's codes and CF standard names. It is already supporting automatic DIF creation from CF (translating Standard Names to GCMD Science Keywords) and SeaDataNet metadata creation from CF (translating Standard Names to BODC Parameter Usage Vocabulary terms). For example see:
http://vocab.ndg.nerc.ac.uk/term/P071/current/CFSN0335
This delivers a dynamically generated RDF (actually SKOS) document describing the CF Standard Name 'sea_water_temperature' and its mappings to GCMD (the URL containing 'P041') and BODC (the URL containing 'P021'). I Martin provided his vocabulary plus a mapping to Standard Names I could put it up on the server fairly quickly as a short-term measure.
Cheers, Roy.
>>> Jonathan Gregory <j.m.gregory at reading.ac.uk> 4/10/2008 8:37 am >>>
Dear Martin
I believe there used to be an xsd file for the standard_name xml file. Perhaps
Velimir (copied) knows where it is?
I sympathise with the need for equivalences to CF metadata and that is of
course why the PCMDI and GRIB equivalences were set up in the first place.
However, I would say there are two reasons why putting equivalences in the
standard_name xml file is not the best approach:
* There is probably not a one-to-one correspondence between your variables
and standard names. I expect some of your variables might imply other CF
metadata as well, as is the case with some of the PCMDI and GRIB codes. This
is not recorded in the standard_name xml file, but it is noted in the separate
tables for GRIB codes and PCMDI names at
http://cf-pcmdi.llnl.gov/documents/cf-standard-names/
e.g. tas means not just air_temperature, but implies a vertical coordinate.
* The equivalence between your variables and CF metadata is not really part
of the CF convention, although it facilitates the use of CF, and it seems a
arbitrary to include equivalences to a selection of other conventions.
As I mentioned, for these reasons I think we should remove the AMIP and PCMDI
equivalences from the table. In any case, they are not being maintained and
are out of date, and probably wrong for some GRIB codes.
I feel that a better approach is to have a separate xml/html table for the
equivalence between CF metadata (not just standard names, but standard name
+ other metadata, more like common concepts) and other metadata, one for each
standard (GRIB, AMIP, HTAP, aerocom, etc.). These tables could be linked to
the CF site and would not be upset by updates to the standard name table,
because we never *delete* standard names, so the equivalences would always
remain valid. Do you think that would work?
I am sure that others have good ideas about this, having thought about mappings
and ontologies and how they should be maintained.
Best wishes
Jonathan
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Received on Thu Apr 10 2008 - 02:20:37 BST
