Re: [CF-metadata] Proposal for additional CF biogeochemistry attributes
Dear Olivier, As an atmospheric chemist I have three remarks on your list: 1) volume_concentration_of_oxygen_in_sea_water [vol/vol] For atmospheric chemistry we have defined the following measures to express a tracers' abundance: mass_concentration [kg/m3] mole_concentration [mole/m3] mole_fraction [mole/mole] moles [moles] You suggest now to add volume concentration. I think we should avoid to add too many expressions. In your case, I assume that this is the common way to express this quantity in ocean science, but if not, could you possibly use one of the existing expressions? 2) ratio_of_nitrate_to_phosphate_in_sea_water Does this refer name to the mass or volume or mole ratio? 3) The post fix in_sea_water All your names refer to quantities in the ocean which is a large scale medium, not a local one. I guess a local medium in the oean would rather be something like in_air if a tracer is contained in air bubbles in the ocean. I am not sure how to deal with this, but should ocean_ (or sea_water_) not be used as a prefix with the post fix deleted? Best regards, Christiane ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
[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@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] new standard name request for pH
Dear all, I am not an expert ocean acidification at all, but there are some general questions I have concerning these names for the pH of sea water: 1) large scale medium Why not use sea_water (or ocean_) as a prefix as we have agreed on? 2) definded_by For the atmospheric chemistry names we have used expressed_as, why not use this here as well? 3) definition of pH (-log(H+)) As far as I know the pH is defined as the negative logarithm of the concentration of H+ (or whatever else), this is missing in the suggested names. I would suggest to use expressed_as instead of defined_by to circumvent this problem. 4) definition of pH (N.B.S or free) I have checked the different definitions of the pH in sea water and it seems to me that the NBS and the free pH do not all refer to the concentration of H+ alone but consider also other ions, please see http://en.wikipedia.org/wiki?title=Talk:Ocean_acidification#cite_note-zeebe-0 (rather bad page, but still..) Am I confused? 5) concentration For the atmospheric chemistry names we have mass_concentration and mole_concentration which is mass or mole per volume. This means that concentration always means per unit volume, and not per unit mass. If you say now concentration per unit mass, this is confusing. Best regards, Christiane ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
[CF-metadata] new standard name request for pH
Dear John - The vague term violates the concept of consistent units, doesn't it I don't think so. pH is dimensionless. However, because it is dimensionless, the exact definition has to state the unit of mass or volume being used, to get the right numbers. Boussinesq models (most ocean climate models are Boussinesq) treat density as constant 1000 kg m-3 except in the computation of pressure gradients, where it matters to the dynamics. Therefore in dealing with concentrations of tracers, per kg and per litre are identical and to choose one or the other would be arbitrary and hence unhelpful for data exchange. - The interest in making things clear to the chemist seems to be at the cost of making things straightforward to the people who work with sea water pH. This is an issue similar to many we have had before. CF stdnames are intended to be interdisciplinary. The use of a longer, explicit term in standard names does not imply that there is anything wrong with the usual terminology. It is simply intended to make things clearer to non-experts. I believe this approach is a strength of CF standard names. What is confusing, perhaps, is that we call them names, which might suggest we should stick to the most familiar terms. We use familiar terms whenever we can, but often with added precision. Best wishes Jonathan ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] new standard name request for pH
Hi Christiane, Please check out the previous postings. There are in fact 3 pH scales covering pH based on a concentration per kg: one based on H+, a second on H+ and bisulphate and a third on H+, bisulphate and HF. We did consider having 4 Standard names but I was arguing for just 2 based on H+ alone to try and match the level of specialism covered with other areas. The negative log transform between the appropriate concentration term and 'pH' has always been taken as read by all involved in the discussion, but maybe we should be more explicit when it comes to term definitions. Oceanographers are moving towards expressing chemical data in the dimension moles/kg rather than moles/litre. We need a standardised convention to distinguish these as they have different canonical units and therefore need different Standard Names. I think the approach Jonathan is taking is the most sensible way to do this without large scale deprecation of existing names. We must always remember to include definitions and to read them: they are the key to eliminating confusion. Cheers, Roy. From: cf-metadata-boun...@cgd.ucar.edu [cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Christiane Textor [christiane.tex...@lsce.ipsl.fr] Sent: 30 April 2009 17:13 To: Lowry, Roy K; Jonathan Gregory Cc: cf-metadata@cgd.ucar.edu Subject: Re: [CF-metadata] new standard name request for pH Dear all, I am not an expert ocean acidification at all, but there are some general questions I have concerning these names for the pH of sea water: 1) large scale medium Why not use sea_water (or ocean_) as a prefix as we have agreed on? 2) definded_by For the atmospheric chemistry names we have used expressed_as, why not use this here as well? 3) definition of pH (-log(H+)) As far as I know the pH is defined as the negative logarithm of the concentration of H+ (or whatever else), this is missing in the suggested names. I would suggest to use expressed_as instead of defined_by to circumvent this problem. 4) definition of pH (N.B.S or free) I have checked the different definitions of the pH in sea water and it seems to me that the NBS and the free pH do not all refer to the concentration of H+ alone but consider also other ions, please see http://en.wikipedia.org/wiki?title=Talk:Ocean_acidification#cite_note-zeebe-0 (rather bad page, but still..) Am I confused? 5) concentration For the atmospheric chemistry names we have mass_concentration and mole_concentration which is mass or mole per volume. This means that concentration always means per unit volume, and not per unit mass. If you say now concentration per unit mass, this is confusing. Best regards, Christiane ___ CF-metadata mailing list CF-metadata@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. ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] new standard name request for pH
Hi Roy, Concerning my question 4) I am sorry for not having more carefully read previous postings. You write about concentration per mass. However, I think this is not correct as concentration is generally related to volume in CF as far as I know, see my 5) below. There is mass_concentration and mole_concentration, but both is per unit volume. I have checked old postings and I have found that this has been previously discussed: From godin at mbari.org Wed Jan 3 17:09:34 2007 Date: Wed Jan 3 17:11:17 2007 Subject: [CF-metadata] Proposed standard names for biological model outputs In text books mole/mass is referred to as molality, but this is not a commonly used expression. Anyway, I think if we use concentration in different ways than previously defined, this will lead to confusion. Best regards, Christiane Lowry, Roy K a écrit : Hi Christiane, Please check out the previous postings. There are in fact 3 pH scales covering pH based on a concentration per kg: one based on H+, a second on H+ and bisulphate and a third on H+, bisulphate and HF. We did consider having 4 Standard names but I was arguing for just 2 based on H+ alone to try and match the level of specialism covered with other areas. The negative log transform between the appropriate concentration term and 'pH' has always been taken as read by all involved in the discussion, but maybe we should be more explicit when it comes to term definitions. Oceanographers are moving towards expressing chemical data in the dimension moles/kg rather than moles/litre. We need a standardised convention to distinguish these as they have different canonical units and therefore need different Standard Names. I think the approach Jonathan is taking is the most sensible way to do this without large scale deprecation of existing names. We must always remember to include definitions and to read them: they are the key to eliminating confusion. Cheers, Roy. From: cf-metadata-boun...@cgd.ucar.edu [cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Christiane Textor [christiane.tex...@lsce.ipsl.fr] Sent: 30 April 2009 17:13 To: Lowry, Roy K; Jonathan Gregory Cc: cf-metadata@cgd.ucar.edu Subject: Re: [CF-metadata] new standard name request for pH Dear all, I am not an expert ocean acidification at all, but there are some general questions I have concerning these names for the pH of sea water: 1) large scale medium Why not use sea_water (or ocean_) as a prefix as we have agreed on? 2) definded_by For the atmospheric chemistry names we have used expressed_as, why not use this here as well? 3) definition of pH (-log(H+)) As far as I know the pH is defined as the negative logarithm of the concentration of H+ (or whatever else), this is missing in the suggested names. I would suggest to use expressed_as instead of defined_by to circumvent this problem. 4) definition of pH (N.B.S or free) I have checked the different definitions of the pH in sea water and it seems to me that the NBS and the free pH do not all refer to the concentration of H+ alone but consider also other ions, please see http://en.wikipedia.org/wiki?title=Talk:Ocean_acidification#cite_note-zeebe-0 (rather bad page, but still..) Am I confused? 5) concentration For the atmospheric chemistry names we have mass_concentration and mole_concentration which is mass or mole per volume. This means that concentration always means per unit volume, and not per unit mass. If you say now concentration per unit mass, this is confusing. Best regards, Christiane ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata -- == Christiane Textor Laboratoire des Sciences du Climat et de l'Environnement Unite Mixte de Recherche CEA-CNRS-UVSQ LSCE/IPSL laboratoire CEA/CNRS/UVSQ Saclay, Orme des Merisiers, Bat. 701, Piece 3b, Point Courrier 129 F-91191 Gif-sur-Yvette Cedex FRANCE mailto: christiane.tex...@lsce.ipsl.fr Tel ++33 1 69 08 34 07 Fax ++33 1 69 08 77 16 GEOmon scientific coordinator http://www.geomon.eu == ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
Re: [CF-metadata] new standard name request for pH
Hi Again, Like it or not the oceanograpghic domain is using: mass of solute per volume of solvent mass of solute per unit mass of solvent moles of solute per unit volume of solvent moles of solute per unit mass of solute volume of solute per unit mass of solvent volume of solute per unit volume of solvent depending on community within the domain. Following my understanding of CF each of these needs to be addressed by the Standard Name system through a consistent syntax. What we need to do is establish a convention for this, which is what I see Jonathan's efforts addressing. Any advances on his conventions obviously need consideration. Cheers, Roy. From: Christiane Textor [christiane.tex...@lsce.ipsl.fr] Sent: 30 April 2009 20:41 To: Lowry, Roy K; Lowry, Roy K Cc: cf-metadata@cgd.ucar.edu Subject: Re: [CF-metadata] new standard name request for pH Hi Roy, Concerning my question 4) I am sorry for not having more carefully read previous postings. You write about concentration per mass. However, I think this is not correct as concentration is generally related to volume in CF as far as I know, see my 5) below. There is mass_concentration and mole_concentration, but both is per unit volume. I have checked old postings and I have found that this has been previously discussed: From godin at mbari.org Wed Jan 3 17:09:34 2007 Date: Wed Jan 3 17:11:17 2007 Subject: [CF-metadata] Proposed standard names for biological model outputs In text books mole/mass is referred to as molality, but this is not a commonly used expression. Anyway, I think if we use concentration in different ways than previously defined, this will lead to confusion. Best regards, Christiane Lowry, Roy K a écrit : Hi Christiane, Please check out the previous postings. There are in fact 3 pH scales covering pH based on a concentration per kg: one based on H+, a second on H+ and bisulphate and a third on H+, bisulphate and HF. We did consider having 4 Standard names but I was arguing for just 2 based on H+ alone to try and match the level of specialism covered with other areas. The negative log transform between the appropriate concentration term and 'pH' has always been taken as read by all involved in the discussion, but maybe we should be more explicit when it comes to term definitions. Oceanographers are moving towards expressing chemical data in the dimension moles/kg rather than moles/litre. We need a standardised convention to distinguish these as they have different canonical units and therefore need different Standard Names. I think the approach Jonathan is taking is the most sensible way to do this without large scale deprecation of existing names. We must always remember to include definitions and to read them: they are the key to eliminating confusion. Cheers, Roy. From: cf-metadata-boun...@cgd.ucar.edu [cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Christiane Textor [christiane.tex...@lsce.ipsl.fr] Sent: 30 April 2009 17:13 To: Lowry, Roy K; Jonathan Gregory Cc: cf-metadata@cgd.ucar.edu Subject: Re: [CF-metadata] new standard name request for pH Dear all, I am not an expert ocean acidification at all, but there are some general questions I have concerning these names for the pH of sea water: 1) large scale medium Why not use sea_water (or ocean_) as a prefix as we have agreed on? 2) definded_by For the atmospheric chemistry names we have used expressed_as, why not use this here as well? 3) definition of pH (-log(H+)) As far as I know the pH is defined as the negative logarithm of the concentration of H+ (or whatever else), this is missing in the suggested names. I would suggest to use expressed_as instead of defined_by to circumvent this problem. 4) definition of pH (N.B.S or free) I have checked the different definitions of the pH in sea water and it seems to me that the NBS and the free pH do not all refer to the concentration of H+ alone but consider also other ions, please see http://en.wikipedia.org/wiki?title=Talk:Ocean_acidification#cite_note-zeebe-0 (rather bad page, but still..) Am I confused? 5) concentration For the atmospheric chemistry names we have mass_concentration and mole_concentration which is mass or mole per volume. This means that concentration always means per unit volume, and not per unit mass. If you say now concentration per unit mass, this is confusing. Best regards, Christiane ___ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata -- == Christiane Textor Laboratoire des Sciences du Climat et de l'Environnement Unite Mixte de Recherche CEA-CNRS-UVSQ LSCE/IPSL laboratoire CEA/CNRS/UVSQ Saclay, Orme des Merisiers, Bat. 701, Piece 3b, Point Courrier 129 F-91191
