[CF-metadata] "positive" attribute

[Bryan Lawrence]

Your original email started me worrying about a number of things. I'm aware 
that we're busy building standard names with embedded sign conventions, and 
I'm not entirely comfortable about that. 

What happens if I build (or have) a model which happens to have a different 
sign convention than the one chosen thus far? Do I have to reprocess all my 
data, or introduce a duplicate set of standard names with the opposite 
convention embedded. The latter doesn't seem right!

I would rather we expanded the use of the positive attribute in a sensible 
manner in conjunction with new groupings of standard names. 

Bryan




On Thursday 28 June 2007 14:45:11 Forrest Hoffman wrote:
> Bryan:
>
> Jonathan Gregory has been offering suggestions and help off list for a
> suite of new standard_names I would like to propose.  Jonathan pointed
> out that the sign convention is specified in the standard_name, so use
> of the "positive" attribute is not needed.
>
> Thanks!
>
> Forrest
>
> Bryan Lawrence wrote:
> > Hi Forrest
> >
> > Are some of these going to be implicit in the standard name? (I imagine
> > no always, so I can see the sense of the argument). Personally I don't
> > have a problem with introducing an extended controlled vocabulary into
> > the positive argument.
> >
> > Cheers
> > Bryan
> >
> > On Tuesday 26 June 2007 15:03:31 Forrest Hoffman wrote:
> >> Much of the CF-1.0 convention seems to be atmospherically biased.  I
> >> know that's because it is the atmospheric scientists that pioneered all
> >> these developments.  In attempting to adopt this methodology for other
> >> components of Earth System Models, I'm concluding it may be necessary to
> >> extend the convention to adequately support the needs of these
> >> components.
> >>
> >> For example, it appears to me that the "positive" attribute for CF-1.0
> >> variables is really used to describe vertical directionality.  This
> >> attribute is often traditionally associated with atmospheric radiation
> >> variables.  In CMOR, the only valid attribute values are "up" and
> >> "down."
> >>
> >> In terrestrial biogeochemistry various sign conventions exist, and I had
> >> hoped to use the "positive" attribute to describe the desired convention
> >> where vertical directionality is not important or known.  The values I
> >> had initially hoped to use for the "positive" attribute for some
> >> biogeochemistry variables were "into biosphere" and "out of biosphere"
> >> and "into pool" and "out of pool."
> >>
> >> It would seem that "vertical-directionality" would be a more appropriate
> >> attribute where the "positive" attribute has been traditionally
> >> applied.  I'm sure nobody wants to change this now, but I'm looking for
> >> suggestions for attributes that might describe sign conventions where
> >> directionality is either not vertical or is more conceptually abstract.
> >> We could establish a "negative" attribute, but users might expect some
> >> kind of correspondence with the "positive" attribute.  A
> >> "sign-convention" attribute might work, but it might have many possible
> >> values.  Any other suggestions?
> >>
> >> Forrest