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
