[CF-metadata] standard_name modifiers

From: Schultz, Martin <m.schultz>
Date: Fri, 25 Feb 2011 14:56:28 +0100

Dear Jonathan,

    I don't quite agree with the implication you derive from : "In general, CF metadata describes what a quantity *is* and not how it was calculated from other quantities." -- a temperature difference is a temperature, but you don't want to confuse it with a temperature (pun intended). Suppose you have this wonderful search engine that finds out that NOAA, UK Met Office, JMA, ECMWF and many others provide daily fields of sea surface temperatures. Then you load them all and compute a mean value. What happens if the NOAA values are SST anomalies rather than actual temperatures? As far as I can tell, the software would have no way of telling. OK: you can argue this is why we still need humans, but in my view it defeats the GEOSS concept of interoperability. In particular, because it should be avoidable. But perhaps a simple solution yould be to add a standard_name modifier called "derived_quantity" which would mean that it has similar properties (grid, units, etc.) like the original, but values should not be c
ompared with the original.

Best,

Martin


>
> It would probably help if we focussed on some real use-cases
> where it is essential to provide *systematic* metadata i.e.
> which can be processed by programs. It is always possible to
> provide descriptive metadata, useful to humans, in
> non-standardised attributes such as long_name and history,
> and this can explain how the quantity is obtained.
>
> Best wishes
>
> Jonathan
>

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Received on Fri Feb 25 2011 - 06:56:28 GMT