Hi Jonathan,
Not quite the correct interpretation. Both NBS and free scale are based on the number of moles of hydrogen ions. The difference is that NBS referes to the number of moles in a litre of water whereas free scale refers to the number of moles in a kilogram of water. So following your logic we should really have:
pH_of_sea_water_defined_by_mole_concentration_of_hydrogen_ion_per_unit_mass (free scale)
pH_of_sea_water_defined_by_mole_concentration_of_hydrogen_ion_per_unit_volume (NBS)
This certainly fulfils my 'does what is says on the tin' criterion!
Having the Standard Name 'pH_of_sea_water' defined as 'pH defined on any scale: past, present or future' appeals to the pragmatic side of my nature but others, particularly carbonate system chemists, might see it as inviting bad practice. With me pragmatism wins, so I'd give your suggestion a tentative 'yes' vote but would be prepared to back down if there were strong objections from elsewhere in the CF community.
Cheers, Roy.
-----Original Message-----
From: cf-metadata-bounces at cgd.ucar.edu [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Jonathan Gregory
Sent: 30 April 2009 15:16
To: cf-metadata at cgd.ucar.edu; Lowry, Roy K
Subject: [CF-metadata] new standard name request for pH
Dear Roy
> The two pH variants I knew of before I prodded John for information were NBS, which is based on hydrogen ion concentration per unit volume (moles/litre), and free scale based on hydrogen ion concentration per unit mass (moles/kg).
Ah, I see.
> pH_per_unit_mass_in_sea_water for free scale
> pH_per_unit_volume_in_sea_water for NBS
They're not really pH per unit something, but H per unit something expressed
as pH, aren't they. What about
pH_of_sea_water_defined_by_mass_concentration_of_hydrogen_ion
pH_of_sea_water_defined_by_mole_concentration_of_hydrogen_ion
and just
pH_of_sea_water
for applications which don't want to be precise.
Cheers
Jonathan
_______________________________________________
CF-metadata mailing list
CF-metadata at cgd.ucar.edu
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
--
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 is exempt from release under the Act. Any material supplied to
NERC may be stored in an electronic records management system.
Received on Thu Apr 30 2009 - 08:35:07 BST
