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, p...@llnl.gov, Lawrence Livermore National Lab.
-----------------------------------------------------------------------
> -----Original Message-----
> From: CF-metadata [mailto:cf-metadata-boun...@cgd.ucar.edu] On Behalf Of
> Jonathan Gregory
> Sent: Wednesday, September 19, 2012 7:45 AM
> To: cf-metadata@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
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