There was a github issue opened on UDUNITS2 a few years back (still open, btw) regarding the support for PSU in the package:
https://github.com/Unidata/UDUNITS-2/issues/27 An interesting point is made regarding units and physical quantities. Sean On Tue, Jul 18, 2017 at 7:12 AM, V. Balaji - NOAA Affiliate <[email protected]> wrote: > The ocean modeling community is adamant that they will continue to use PSUs > for salinity: it's this unit, rather than its SI or dimensionless > equivalent, that gives the maximum digits of precision in a floating-point > representation of salinity. > > It's a valid concern, and CF should perhaps reconsider, with a new > discussion giving weight to the views of modelers as well as physical > oceanographers. > > Thanks, > > Lowry, Roy K. writes: > >> Hello Martin, >> >> >> This topic has been debated at length in CF. To cut a long story short, >> the term 'Practical Salinity Unit' was coined when the 1978 Practical >> Salinity scale was devised. However, the term fell out of favour with the >> physical oceanographic community whose current recommended practice is that >> Practical Salinity - a ratio - should be a dimensionless number. CF >> followed this recommendation and so PSU is not a part of CF. >> >> >> Have a dig around in the mailing list archive if you want to find out >> more. >> >> >> Cheers, Roy. >> >> >> Please note that I partially retired on 01/11/2015. I am now only working >> 7.5 hours a week and can only guarantee e-mail response on Wednesdays, my >> day in the office. All vocabulary queries should be sent to >> [email protected]. Please also use this e-mail if your requirement is >> urgent. >> >> >> ________________________________ >> From: CF-metadata <[email protected]> on behalf of >> [email protected] <[email protected]> >> Sent: 18 July 2017 13:43 >> To: [email protected]; [email protected]; >> [email protected] >> Subject: [CF-metadata] Is "psu" a valid cf unit? >> >> Hello David, all, >> >> Is "psu" a valus CF unit? It is not in Udunits, but it is added in >> cf-python as a unit alias and also appears to be accpeted by the cf-checker. >> I can't see any mention of it in the CF Convention document: the latter only >> lists level, layer, and sigma_level permitted departures from Udunits, >> >> regards, >> Martin >> >> _______________________________________________ >> CF-metadata mailing list >> [email protected] >> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >> CF-metadata Info Page - University Corporation for >> ...<http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata> >> mailman.cgd.ucar.edu >> This is an unmoderated list for discussions about interpretation, >> clarification, and proposals for extensions or change to the CF conventions. >> >> >> >> ________________________________ >> 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. >> ________________________________ >> > > -- > V. Balaji Office: +1-609-452-6516 > Head, Modeling Systems Group, GFDL Mobile: +1-917-273-9824 > Princeton University Email: [email protected] > https://www.gfdl.noaa.gov/v-balaji-homepage > > _______________________________________________ > CF-metadata mailing list > [email protected] > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
