[CF-metadata] new standard name proposal for total ozone in DU

Jonathan Gregory j.m.gregory at reading.ac.uk
Fri Dec 7 06:31:23 MST 2012

Dear Martin

>     Philip also raises a good point with respect to alias names: has it been stated clearly that they must refer to "exactly the same quantity"? I believe they should, because if we allow "trivial" unit conversions to count as aliases, then even "wavelength" and "frequency" could be considered of aliases, which surely no one would want.

It does not say explicitly in your terms, but the convention (Appendix B)
implies that the alias has the same definition as the quantity of which it
is an alias, which I would say means it is exactly the same quantity. As
Philip says, these quantities cannot be the same because they have different
physical dimensions, even though the values may be numerically equal.

I tend to think it should be sufficient to point out the alternative in the
definition of each of these quantities (the one in mm and the one in mol m-2).
Deprecation of a quantity would be a step further than CF usually takes. CF
provides metadata for things people want to describe, rather than prescribing
which things they ought to describe.

Best wishes


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