Hi Alison,
A technical solution could be found, but I would be more comfortable with a universally understandable canonical unit that didn't enforce a particular scaling.
Cheers, Roy.
Please note that I now work part-time from Tuesday to Thursday. E-mail response on other days is possible but not guaranteed!
-----Original Message-----
From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of alison.pamment at stfc.ac.uk
Sent: 05 December 2012 10:30
To: cf-metadata at cgd.ucar.edu
Subject: Re: [CF-metadata] new standard name proposal for total ozone in DU
Dear Roy and Christophe,
As Roy says, we usually use SI units for the canonical unit in the standard name table. There are a few exceptions, for example, age_of_sea_ice has units of year and age_of_surface_snow has units of day, whereas the SI unit for both quantities would be the second. Also, we allowed some of the recently added salinity names to have canonical units of g kg-1 which I'm not sure adheres strictly to SI. I think the reason for having the exceptions was simply that they are the units that are always used with the named quantities.
For Christophe's ozone name, atmosphere_mole_content_of_ozone, the proposed definition is ' "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including content_of_atmosphere_layer are used. The construction "atmosphere_mole_content_of_X" means the vertically integrated number of moles of X above a unit area. The chemical formula for ozone is O3.' Whatever we decide about the units, I think we should add the sentence 'atmosphere_mole_content_of_ozone is usually measured in Dobson Units which are equivalent to 446.2 micromoles m-2'.
Roy's proposed solution of having canonical units of mol m-2 while using Dobson Units in the data files is certainly consistent with the CF conventions. As long as UDUNITS knows how to convert the units in the file to the canonical units there is no problem. Christophe, would that be acceptable to the ozone community?
Roy, is there any technical reason why we couldn't map to Dobson Units in the vocabulary server if that were the preferred solution?
Best wishes,
Alison
------
Alison Pamment Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre Email: alison.pamment at stfc.ac.uk
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.
> -----Original Message-----
> From: Lowry, Roy K. [mailto:rkl at bodc.ac.uk]
> Sent: 04 December 2012 10:23
> To: Christophe Lerot
> Cc: Pamment, Alison (STFC,RAL,RALSP); cf-metadata at cgd.ucar.edu
> Subject: RE: [CF-metadata] new standard name proposal for total ozone
> in DU
>
> Hello Cristophe,
>
> To be absolutely clear, I'm saying the data should be stored in the
> NetCDF in Dobson Units, that the units parameter attribute in the
> NetCDF file should be Dobson Units, but that the canonical unit in the
> Standard Names List and therefore the units mapped in our server
> should be moles per square metre.
>
> Cheers, Roy.
>
> ________________________________________
> From: Christophe Lerot [Christophe.Lerot at aeronomie.be]
> Sent: 04 December 2012 10:20
> To: Lowry, Roy K.
> Cc: alison.pamment at stfc.ac.uk; cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] new standard name proposal for total ozone
> in DU
>
> Dear Roy,
>
> Do you mean that the total ozone values should be given in moles per
> square metre in the NetCDF files themselves? Or do you mean that I
> should simply add a specific comment in the unit parameter attribute
> to make clear that the values are provided in Dobson Unit?
> The Dobson Unit is quite common for total ozone users and I'd prefer
> to stay with this unit if possible.
>
> Cheers,
> Christophe
>
> On 3/12/2012 15:39, Lowry, Roy K. wrote:
> > Hello Alison,
> >
> > Surely the canonical unit for Dobson Units would be moles per square
> metre, with Dobson Units appearing as the scaled unit in the units
> parameter attribute. Making Dobson Units the canonical unit would be
> like having cm/s rather than m/s as a canonical unit.
> >
> > Cheers, Roy.
> > ________________________________________
> > From: CF-metadata [cf-metadata-bounces at cgd.ucar.edu] On Behalf Of
> alison.pamment at stfc.ac.uk [alison.pamment at stfc.ac.uk]
> > Sent: 03 December 2012 14:18
> > To: cf-metadata at cgd.ucar.edu
> > Subject: Re: [CF-metadata] new standard name proposal for total
> > ozone in
> DU
> >
> > Dear Christophe and Jonathan,
> >
> > I also support this proposal. We don't currently have any standard
> > names
> that use Dobson Units - I think UDUnits1 didn't support it. However,
> since it is defined in UDunits2 I don't see any problem with adding it.
> >
> > Best wishes,
> > Alison
> >
> > ------
> > Alison Pamment Tel: +44 1235 778065
> > NCAS/British Atmospheric Data Centre Email:
> alison.pamment at stfc.ac.uk
> > STFC Rutherford Appleton Laboratory
> > R25, 2.22
> > Harwell Oxford, Didcot, OX11 0QX, U.K.
> >
> >
> >
> >> -----Original Message-----
> >> From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On
> Behalf
> >> Of Jonathan Gregory
> >> Sent: 27 November 2012 20:52
> >> To: cf-metadata at cgd.ucar.edu
> >> Subject: [CF-metadata] new standard name proposal for total ozone
> >> in
> DU
> >>
> >> Dear Christophe
> >>
> >>> So I'd like to propose the following variable name for total ozone
> >>> columns based on recommendations I was given:
> >>> - "atmosphere_mole_content_of_ozone" expressed in Dobson Units.
> >>> Dobson Unit (DU) is already defined in the UDUNIT package ans is
> >>> equivalent to 446.2 micromoles m-2.
> >> This seems fine to me. It is consistent in construction with
> >> existing names for a quantity in mol m-2.
> >>
> >> Best wishes
> >>
> >> Jonathan
> >> _______________________________________________
> >> CF-metadata mailing list
> >> CF-metadata at cgd.ucar.edu
> >> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
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> >
> > This message (and any attachments) is for the recipient only. NERC
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> this email and any reply you make may be disclosed by NERC unless it
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> --
> -----------------------------------------------------
> Dr. Christophe LEROT
> Belgian Institute for Space Aeronomy
> Chemistry & Physics of Atmospheres
> Avenue circulaire, 3
> 1180 Brussels
> Belgium
> phone: +32/(0)2-3730-407
> mobile: +32/(0)472-81.87.00
> mail: christophe.lerot at aeronomie.be
> url: http://uv-vis.aeronomie.be/
> -----------------------------------------------------
>
> This message (and any attachments) is for the recipient only. NERC is
> subject to the Freedom of Information Act 2000 and the contents of
> this email and any reply you make may be disclosed by NERC unless it
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> may be stored in an electronic records management system.
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Received on Wed Dec 05 2012 - 03:51:14 GMT
