Hi All,
Reinforcing Martin's point, if a plotting package produces plots labeled with
1e-9 as a unit, I will manually edit the plot to replace the unit with mol/mol,
kg/kg, Kg(CH4)/kg(air), or whatever is appropriate. Otherwise it produces
great confusion, since the numerical values are different, but not different
enough to be obvious. I have seen too many presentations where the units are
not clear, or get mixed up within a single talk.
Obviously it would be desirable for the end user if the plotting package put
the appropriate unit on automatically. This could be done fairly easily by
having a dictionary within the plotting package linked to the std_name, as
Martin suggests (or by using grammar rules if/when that becomes standardized),
but it would be putting the burden on the plotting package developers to
maintain the dictionary.
Best wishes,
Philip
-----------------------------------------------------------------------
Dr Philip Cameron-Smith, [email protected], Lawrence Livermore National Lab.
-----------------------------------------------------------------------
> -----Original Message-----
> From: [email protected] [mailto:cf-metadata-
> [email protected]] On Behalf Of Schultz, Martin
> Sent: Thursday, April 14, 2011 12:24 PM
> To: [email protected]
> Subject: Re: [CF-metadata] physical vs dimensional units
>
>
> > Message: 6
> > Date: Wed, 13 Apr 2011 14:52:26 -0600
> > From: Steve Emmerson <[email protected]>
> > Subject: Re: [CF-metadata] physical vs dimensional units
> > To: [email protected]
> > Message-ID: <[email protected]>
> > Content-Type: text/plain; charset=ISO-8859-1
> >
> > On 04/13/2011 02:25 PM, John Caron wrote:
> > > the point im trying to make is that it would be better to
> understand
> > > that "mol mol-1" (canonical udunit = 1) is not the same as "m3 m-
> 3"
> > > (canonical udunit = 1).
> >
> > In my opinion, the distinction between "mol/mol" and "m3/m3" is
> better
> > indicated by the name of the physical quantity being displayed rather
> > than by its unit attribute. In the cases under consideration, the
> > respective physical quantities would be "amount of substance
> fraction"
> > and "volume fraction".
> >
> > See Table 12 of
> > <http://physics.nist.gov/Pubs/SP811/sec08.html> for more
> > information.
> >
> > For example, the Y-axis of a plot could be labeled "Amount of
> > Substance
> > Fraction of Carbon / 1e-9" to plot nanomoles of carbon per
> > mole of whatever.
>
> Sorry, Steve - but if I would suggest this to any of my colleagues,
> they would declare me as insane. And according to the principle that
> "short and concise is beautiful", I would also much rather continue to
> see plots labeled as "C2H4 [nmolC/mol]" instead of "Amount of C2H4
> fraction of carbon / 1e-9".
>
> I can see the point that this may not be solved by tweaking the units
> attribute. But it means that software that wants to automate the use of
> CF data and present them to users will have to have more "intelligence"
> (well, actually a rather simple dictionary) built in. It's one of those
> areas where good principles collide with pragmatism. Here I see a
> majority of the CF community tending to principles - there were other
> cases in this discussion list where pragmatism reigned.
>
> Cheers,
>
> Martin
>
>
>
> -----------------------------------------------------------------------
> -------------------------
> -----------------------------------------------------------------------
> -------------------------
> Forschungszentrum Juelich GmbH
> 52425 Juelich
> Sitz der Gesellschaft: Juelich
> Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498
> Vorsitzender des Aufsichtsrats: MinDirig Dr. Karl Eugen Huthmacher
> Geschaeftsfuehrung: Prof. Dr. Achim Bachem (Vorsitzender),
> Dr. Ulrich Krafft (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt,
> Prof. Dr. Sebastian M. Schmidt
> -----------------------------------------------------------------------
> -------------------------
> -----------------------------------------------------------------------
> -------------------------
>
> Besuchen Sie uns auf unserem neuen Webauftritt unter www.fz-juelich.de
> _______________________________________________
> CF-metadata mailing list
> [email protected]
> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
_______________________________________________
CF-metadata mailing list
[email protected]
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
