[GO-ESSP] Units and NERC DataGrid

[Roy Lowry]

Bryan/Peter,

I have been giving some thought about what to do about units in NERC
DataGrid as we get to the stage where vocabularies become today's
problem rather than tomorrow's.

The first issue to address is what to do about standardisation.  The
oceanographic community has been trying for years to standardise the
units people use for specific parameters.  The degree of success, with
good reason, has declined dramatically as one goes from physical to
chemical to biological domains.  It is therefore clear that in NERC
DataGrid we are going to have to deal with the situation where different
data hosts store the same parameter in different units.  In other words,
whilst we can recommend standardisation I cannot see how we can enforce
it and so we need to engineer for what's really out there (remember I
deal in measurements, not model outputs).

The solution has to lie in the philosophical approach taken by UDUNITS,
but this will require significant extension to do the job we need.  We
also need to take a more pragmatic approach than
dimensionality/canonical units to allow interoperability between data
sets where scale not dimensionality is the issue.

I also feel that what we need is more along the lines of a semantic web
resource rather than a downloadable executable approach: in other words
a units ontology that provides a units vocabulary plus the knowledge
about which units may be interconverted and how.  Such an ontology could
be interlinked with parameter vocabularies indicating the subset of
units that may sensibly be associated with particular parameters.

Before embarking on building such an ontology for NERC DataGrid, I am
circulating this e-mail far and wide (apologies for  multiple postings)
to obtain answers to two simple questions.

What do you think of this approach?

More importantly:

Does anybody know of anybody who is building/has built such an ontlogy
and can save me a job?

Cheers, Roy

 



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