Hi Jonathan
I think it's quite clear that the vertical components don't fit into the
algorithm you describe. What about helping software plot residual mean
circulations? Wind barbs, whatever. I'd like software to direct users what
things are vectors ... so I utterly agree with Bert. Otherwise we'll have to
put it in external metadata (the CF pages are external metadata, and far too
unresponsive for this application).
Note that i am not suggesting a change to the standard names, i'm suggesting a
new way of linking variables. We already suspect we have to do this for
grids ...
... and I'm sure it would simplify vector handling. Code can simply ignore
assocations it doesn't understand, but providing directives helps code
writers.
I don't really understand the objection. We have at least one use case for
doing so (Bert's), and he's already indicated that if we don't do it in CF
he'll do it in an external file ... which is nuts ...
I don't have time to write out a formal proposal, but it doesn't need to be
complicated. Just a set of new file attributes that link variables with
assocations from a (new) controlled vocabulary.
Cheers
Bryan
On Monday 20 March 2006 15:00, Jonathan Gregory wrote:
> Dear Bryan
>
> I think that we don't need to build such structure into the data
> which is written. Given that east/north and x/y components can be easily
> identified by text substitutions in the standard names, it would be
> straightforward to write a program to generate a list of the vector
> quantities (i.e. the input file which Bert wants) from the standard name
> table. No extra information is required to do this, so it would be an
> unnecessary complication of the convention, I feel. We can provide such a
> list on the CF web site if it's generally useful.
>
> (The algorithm is that if you can find two names of the general form
> [A_]eastward[_B] and [A_]northward[_B], where A and B are the same in the
> two cases, they are components of a vector quantity A_B. Similarly with x
> and y components.)
>
> Factorising the standard name into bits has the effect of meaning more
> attributes have to be checked by data-reading programs, and the data is
> more complicated to write. I don't see an advantage in doing it except
> where the bits might be multi-valued coordinates.
>
> Best wishes
>
> Jonathan
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--
Bryan Lawrence
Director of Environmental Archival and Associated Research
Head of the NCAS/British Atmospheric Data Centre
CCLRC, Rutherford Appleton Laboratory
Phone +44 1235 445012; Fax ... 5848; Web: home.badc.rl.ac.uk/lawrence
Received on Mon Mar 20 2006 - 08:30:49 GMT
