Hi Rich, I should clarify that my comment was following on from Nan's and referred only to practical salinity, otherwise known as PSS-78. Absolute salinity has dimensions mass/mass and so is not dimensionless.
Cheers, Roy. ________________________________________ From: Signell, Richard [rsign...@usgs.gov] Sent: 22 May 2015 20:01 To: Lowry, Roy K. Cc: Reyna Jenkyns; cf-metadata@cgd.ucar.edu; OceanSITES Data Management Team; Nan Galbraith; Richard Pawlowicz Subject: Re: [CF-metadata] Salinity units Roy, For sure dimensionless. But "1.0", "0.001" or "g/kg"? The latest version (27) of the CF Standard Name list (http://cfconventions.org/Data/cf-standard-names/27/build/cf-standard-name-table.html) states: sea_water_salinity: "0.001" sea_water_absolute_salinity: "g kg-1" sea_water_practical_salinity: "0.001" sea_water_preformed_salinity: "g kg-1" sea_water_cox_salinity: "0.001" and units packages, of course, would treat "g kg-1" the same as "0.001". Yet in the IOC manual on equation of seawater: http://www.teos-10.org/pubs/TEOS-10_Manual.pdf it states (PDF page 176, printed page 166) that Practical Salinity should have units of "1", while "Absolute Salinity" (the argument used in the toolbox functions) and "Preformed Salinity" (used in numerical ocean models) should have units "g kg-1". So it appears that TEOS agrees with CF on units for Absolute Salinity and Preformed Salinity, but not on Practical Salinity. And OceanSites (as least here: http://www.oceansites.org/docs/OS_PAP-3_201205_P_deepTS.txt) is using "sea_water_practical_salinity" with units of "1", so they are consistent with the TEOS publication, but not the current CF convention (v27). On the TEOS site, there is software to calculate Absolute Salinity from Practical Salinity. So it would seem that the technically correct thing to do would be to use the "gsw_SA_from_SP" routine to convert OceanSites Practical Salinity (in units of "1") to Absolute Salinity (in units of "g/kg") before comparing with the "Preformed Salinity" output "g/kg" from ocean models. I'm pretty confused though, so I'm cc'ing Rich Pawlowicz on this, hoping for his input. Thanks, -Rich On Fri, May 22, 2015 at 1:49 PM, Lowry, Roy K. <r...@bodc.ac.uk> wrote: > Dimensionless. Please???? > > This is the view of physical oceanographers for whom I have the greatest > respect. > > Cheers, Roy. > ________________________________________ > From: Reyna Jenkyns [re...@uvic.ca] > Sent: 22 May 2015 18:06 > To: cf-metadata@cgd.ucar.edu; OceanSITES Data Management Team; Nan Galbraith > Subject: Re: [CF-metadata] Salinity units > > I'm interested in this topic since I didn't realize what had been discussed > previously, and now I think we must be non-compliant as well. Is this > documented formally in the CF documentation? > > Reyna Jenkyns | Data Stewardship Team Lead - Digital Infrastructure > Ocean Networks Canada | T 250 853 3908 | oceannetworks.ca > University of Victoria PO Box 1700 STN CSC 2300 McKenzie Avenue Victoria, BC > V8W 2Y2 > > ________________________________________ > From: CF-metadata <cf-metadata-boun...@cgd.ucar.edu> on behalf of Nan > Galbraith <ngalbra...@whoi.edu> > Sent: Friday, May 22, 2015 10:03 AM > To: cf-metadata@cgd.ucar.edu; OceanSITES Data Management Team > Subject: Re: [CF-metadata] Salinity units > > Hello all - > > It's been a long time, but is anyone interested in re-visiting the subject > of units for practical salinity in CF? > > I was recently notified that my salinity data was likely to be > overlooked by > some users, because I'd used '1' as the units, not '.001'. Somehow, I'd > forgotten the (long-ago) discussion on the CF list about salinity units. > > Some members of the OceanSITES project are interested in revising our > format spec to encourage the use of '1' as an indication that salinity does > not have units - but, of course, we'd mostly rather remain CF-compliant. > > Thanks for any feedback on this. > > Cheers - Nan > > > On 6/17/09 2:48 AM, Lowry, Roy K wrote: > > > Dear All, > > > > During an exercise with Alison mapping the CF Standard Names to a > > units vocabulary in the BODC vocabulary server I noticed that the > > units for salinity were '1.00E-03', i.e. parts per thousand. My > > understanding in that since the introduction of the Practical > > Salinity Scale that salinity is dimensionless with units of '1'. Is > > there agreement for our changing the units in the Standard Name > > table? > > > > Cheers, Roy. > > -- > ******************************************************* > * Nan Galbraith Information Systems Specialist * > * Upper Ocean Processes Group Mail Stop 29 * > * Woods Hole Oceanographic Institution * > * Woods Hole, MA 02543 (508) 289-2444 * > ******************************************************* > > > _______________________________________________ > CF-metadata mailing list > CF-metadata@cgd.ucar.edu > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > _______________________________________________ > 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 -- Dr. Richard P. Signell (508) 457-2229 USGS, 384 Woods Hole Rd. Woods Hole, MA 02543-1598 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
