I see the Jonathan's theoretical position on this one and guess that as the Standard Name is linked to units in the form of dimensionality then there are only two alternatives:
(1) Specify one dimensionality per chemical parameter and force CF-compliant datasets to use that (interconversions are generally simple providing atomic/molecular weights and water density are known). This is what we do in BODC, serving out data values plus dimensionality conversion factors so users can make their own choice, but it's caused a few "debates".
(2) Be prepared for a flood of Standard Names with 4 per chemical parameter. There's not quite as many chemical species as there are biological species, but it the numbers are orders of magnitude up over physical phenomena.
So, I can't defend on the basis of scientific logic, just pragmatism and experience with the problems caused by maintaining and navigating large vocabularies.
Maybe some compromise is needed - say disallow mass and insist on moles?
Cheers, Roy.
>>> Jonathan Gregory <j.m.gregory at reading.ac.uk> 7/28/2006 5:06 pm >>>
Dear Mike et al.
> > spectral_noise_level_in_air: dB : decibels referenced to a sound pressure > of 2x10-5 Pa divided by the square root of frequency in Hz.
> > spectral_noise_level_in_water: dB : decibels referenced to a sound
> > pressure of 1x10-6 Pa divided by the square root of frequency in Hz.
> Since these quantities seem to be closely related to your earlier definitions of sound_pressure_level_in_air|water I wonder if it would be more consistent to use spectral_sound_pressure_level_in_air|water. Also, I am not sure that "noise" is the best term to use here because it could be interpreted as meaning unwanted noise as in "signal to noise ratio". Do you agree?
Alison's suggestions here seem good to me.
> > mass_concentration_of_oxygen_in_sea_water: kg m-3 : Mass of dissolved
> > oxygen per unit volume sea water.
> I note Roy Lowry's concerns below - do we need a separate quantity in different units?
>
> Roy Lowry wrote:
>
> >I worry about 'mass_concentration_of_oxygen_in_sea_water: kg m-3' as we
> > allready have 'moles_of_oxygen_per_unit_mass_in_sea_water' which is
> > effectively the same thing, but in different units. If we start setting
> > up standard names for each chemical species for the various combinations
> > of moles/mass/per litre/per kilogram, we are likely to be overwhelmed.
I disagree with Roy on this. These are dimensionally distinct quantities so
they need different standard names; this is a principle of CF standard names.
The same distinction between mass and mole concentrations has been discussed
for atmos chem names.
Best wishes
Jonathan
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Received on Fri Jul 28 2006 - 10:43:06 BST
