Hi All,
The problem as I see it, is that the two versions of Dobson Unit are effectively equivalent via the ideal gas law. Hence, I see Dobson unit get defined both ways, and since DU is used as the unit the difference is hidden and irrelevant, except for CF because we insist on connecting it back to base units.
If someone has data labeled as DU in a file, we could switch the definition of DU and there would be no science impact unless the software complains.
Which will be easier to change at this point, the units in the CF std-name table or the entry in Udunits?
Either way it would be good to change the description in the CF std_name table to document the issue.
Best wishes,
Philip
-----------------------------------------------------------------------
Dr Philip Cameron-Smith, pjc at llnl.gov, Lawrence Livermore National Lab.
-----------------------------------------------------------------------
> -----Original Message-----
> From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of
> Jonathan Gregory
> Sent: Wednesday, September 19, 2012 7:45 AM
> To: cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] request for new standard name
>
> Dear David and Christophe
>
> > Thinking ahead, I tried to put dobson into cf-python's CF Udunits data
> > base, but couldn't since it was already there (at Udunits version
> > 2.1.24):
> >
> > <unit>
> > <def>446.2 micromoles/meter^2</def>
> > <aliases>
> > <name> <singular>dobson</singular> </name>
> > <symbol>DU</symbol>
> > </aliases>
> > </unit>
> >
> > Would it be too unexpected to give units of "mole/area" to a standard
> > name which started "equivalent_thickness_"?
>
> Thanks for that interesting discovery! mole metres-2 does not have the same
> physical dimensions as metres, so it must be given a different standard name.
> At present we have many atmosphere_mass_content names in kg m-2, and
> many tendency_of_ocean_mole_content names in mol m-2 s-1, so I'd suggest
> the consistent name for this quantity would be
> atmosphere_mole_content_of_ozone in mol m-2, and DU would be
> dimensionally equivalent to that.
>
> Cheers
>
> Jonathan
> _______________________________________________
> CF-metadata mailing list
> CF-metadata at cgd.ucar.edu
> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Received on Wed Sep 19 2012 - 12:20:25 BST
