[CF-metadata] Proposed Standard Names

Bryan Lawrence b.n.lawrence at rl.ac.uk
Tue Sep 20 01:26:11 MDT 2005

Hi Folks

Just as a general point, if we want to maintain as much interoperability 
between vocabs as possible, then we want to avoid as much pushing off of 
semantic information to the coordinate variable ... so I would argue for 
keeping words like "surface" and "back" available as modifiers of standard 

(I know that currently we don't use them as modifiers per se, but we may have 
that option in the future).


On Monday 19 September 2005 23:36, Jonathan Gregory wrote:
> Dear Mike
> Thanks for your reply. I think that clears up pretty much everything. All
> these are agreed:
>  * speed_of_sound_in_sea_water:m s-1
>  * height_above_sea_floor:m
>  * volume_absorption_coefficient_of_radiation_in_sea_water:m-1
>  * volume_attenuation_coefficient_of_radiation_in_sea_water:m-1
>  * volume_scattering_function_of_radiation_in_sea_water:m-1 sr-1
>  * omnidirectional_photosynthetic_spherical_irradiance_in_sea_water:W m-2
>  * omnidirectional_spectral_spherical_irradiance_in_sea_water:W m-3 I
>  * moles_of_oxygen_per_unit_mass_in_sea_water:mol kg-1
>  * moles_of_nitrate_per_unit_mass_in_sea_water:mol kg-1
>  * moles_of_phosphate_per_unit_mass_in_sea_water:mol kg-1
>  * moles_of_silicate_per_unit_mass_in_sea_water:mol kg-1
>  * moles_of_nitrite_per_unit_mass_in_sea_water:mol kg-1
>  * moles_of_nitrate_and_nitrite_per_unit_mass_in_sea_water:mol kg-1
>  * bioluminescent_photon_rate_in_sea_water:s-1 m-3
>  * fractional_saturation_of_oxygen_in_sea_water:1
>  * volume_mixing_ratio_of_oxygen_at_stp_in_sea_water:1
> > I would like to propose that absorption, attenuation, AND scattering
> > should be integrals over all wavelengths, unless there is a coordinate
> > variable specifying range(s) of wavelengths.
> Yes, I agree.
> > On the topic of scattering, I had argued that in addition to a general
> > "scattering" variable, there ought to be a variable called
> > "backscattering". Your reply was that backscattering is just a special
> > case of scattering, and that a coordinate variable should be used to
> > differentiate the two.  Well, I agree that the coordinate variable is
> > important, because there certainly are many angles around which
> > scattering is measured.  However, I would like to propose once again that
> > "back" be retained as a special case of "scattering" in much the same way
> > that "upwelling" and "downwelling" are used modify "radiation", conveying
> > concepts that can be expressed concisely with a coordinate variable, but
> > which are conveyed more clearly with a choice of name.
> Where there are names containing "upwelling" and "downwelling", we do not
> also have a "generic" name that could be either, so it's not an exact
> analogy. Are you proposing we should have *both* of
>  * volume_backwards_scattering_coefficient_of_radiation_in_sea_water:m-1
>  * volume_scattering_coefficient_of_radiation_in_sea_water:m-1
> I think this would be OK if the first is defined to apply to the sum of all
> backward scattering angles, and is not allowed to specify scattering angle
> as a coordinate. If that's a common quantity, I agree it would be useful to
> have a name for it, and probably we should have a correspondingly defined
> "forward" one as well. We have also agreed we need to define
>   * scattering_angle:rad
> > I had used the term "surface" in some of my original proposed variable
> > names... It is probably redundant in the cases I had suggested, since
> > there will often be a coordinate variable that indicates depth or
> > altitude = 0.
> Regarding
>  * partial_pressure_of_carbon_dioxide_in_air:Pa
>  * partial_pressure_of_carbon_dioxide_in_sea_water:Pa
>  * carbon_dioxide_partial_pressure_difference_between_air_and_sea_water:Pa
> If these are surface quantities, I think we should put "surface_" on each
> of them. This is the general rule. The point is that there are many
> coordinates you could equivalently use to indicate "surface", so it's
> inelegant to introduce a single-valued coordinate variable solely for that
> purpose, and makes things complicated for the data-reading program, which
> would have to check for many possibilities.
> > Finally, for sea water flow ... it applies to instruments that have
> > internal measurement elements and require a pump to ensure flow through
> > the measurement elements.  Commonly, the flow rate through these
> > measurement elements is also measured, usually as a quality control
> > check.
> Is it appropriate to have a standard name for this? It sounds rather
> specific to the measurement technique and instrument. Would it often be
> useful to label this quantity in such a way that it could be compared in
> datasets from different sources (the main use of standard names)? If not,
> it might be better to use a long_name for it.
> Best wishes
> Jonathan
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Bryan Lawrence
Head, NCAS/British Atmospheric Data Centre
Director, CCLRC/Environmental Data Archival and Associated Research
badc.nerc.ac.uk, home.badc.rl.ac.uk/lawrence, +44 1235 445012
(CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX)

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