Dear Thomas, and colleagues,
Thank you for bringing this topic back in the spot lights. I made an
attempt to define vectors in CF about 4 years ago. There was a lot of good
discussion in here (
http://cf-trac.llnl.gov/trac/ticket/79) but we
unfortunately never reached a conclusion (although there was some level of
consensus at the start). I will gladely participate to this discussion.
T.
2016-10-27 21:23 GMT+02:00 Clune, Thomas L. (GSFC-6101) <
thomas.l.clune at nasa.gov>:
> I could not find any discussion in the specs about how to indicate that
> two variables are part of a vector pair such as (u,v). In theory one can
> infer the relationship from the long-name, but it would seem to be useful
> to have a more direct means to indicate this relationship.
>
> I see at least 4 different approaches to this:
>
>
> 1. Each variable that is part of a vector has an attribute that names
> the partner component. u:vector_partner = ?v" There is also an attribute
> that specifies the component index: u:vector_index=1 Others may want
> vectors with more components, in which case naming the partners becomes
> more problematic. And then one would also want an attribute that
> specifies the total number of components u:vector_length=2
> 2. Each vector component has an attribute that names the entire vector
> rather than the partner. u:vector_name=?u-v?. There would also be an
> attribute for specifying the vector component index as in (1) above. This
> approach is more scalable for longer vectors, but tools would need to
> search through all variables to find the partner components.
> 3. Have a separate variable which is a vector of strings. Each string
> names the list of component variables with some standard separator. E.g.,
> ?u,v?, ?mx, my?, ?
> 4. Combine components into one variable with an extra vector index
> dimension. But this seems to be contrary to CF conventions for naming
> variables. It is also not very friendly to the tools that we are
> currently using.
>
>
> Thanks in advance,
>
> - Tom
>
>
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>
>
--
==========================================
Thomas Lavergne
Norwegian Meteorological Institute
P.O.BOX 43, Blindern, NO-0313 OSLO, Norway
Phone: (+47) 22963364 <callto:+47%29%2022963364> Skype: thomas.lavergne
<callto:+47%29%2022963380>
Email: t.lavergne at met.no
OSISAF HL Portal: http://osisaf.met.no
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