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[CF-metadata] Encoding Errors on variables in CF

From: Bryan Lawrence <b.n.lawrence>
Date: Thu, 20 Mar 2003 11:14:05 +0000

Hi Jonathan

> variables. However, I am not convinced about introducing a linking
> attribute, because I don't think the relation is so close that it needs to
> be given this special status.

ok, I can accept that argument but ... see below

> In this particular case, you can look for another variable with the same
> spatiotemporal metadata and a standard_name which contains the original one
> as a pattern. That would be very general.

... but I had got the thought from the previous emails that we didn't want to
enforce "error" into standard names ... and I think it would introduce a new
problem:

My radiosonde example is still a good one, and it's real:

For each measurement in a profile I have a number which is an error (which
might be a physical error quantity but is more likely a percentage). So, for
an individual radisonde profile, say of humidity, then I have the
measurement, and an error (let's say a percentage, which increases with
height). So, I can see that I could have two variables in the file which are
the humidity and the error (percentage).

I could then produce a climatology from a year's measurements, and now the
error of interest is the standard error associated with the variance between
measurements within the month and it has rather different units than the
error did in the previous case, still with the same names for the variables
if we were trying to introduce an error standard name for every standard name
... (have i misundestood this point?).

The key point here is that different communties have rather different idea of
what we mean by an error ... even with the same source data ... albeit at
different stages of maturity.

I would have thought it would have been cleaner to have an optional link
between two variables ... software could simply fail gracefully if the link
was broken. This is nothing more than a "data hyperlink" ...

... but I dont feel strongly about this, as long as we can find a sensible way
of doing it ...

Bryan

-- 
Bryan Lawrence, Head NCAS/British Atmospheric Data Centre
web: www.badc.nerc.ac.uk  phone: +44 1235 445012
CLRC: Rutherford Appleton Laboratory, Chilton, Didcot, OX110QX, UK
Received on Thu Mar 20 2003 - 04:14:05 GMT

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