Hello Jonathan,
The reason I'm resurrecting this discussion is that we came under strong pressure from a group of physical oceanographers to use 'dimensionless' with no scaling factor instead of PSU for salinity. I was raising the issue on the list to see how widespread this opinion was.
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: 17 June 2009 08:06
To: cf-metadata at cgd.ucar.edu
Subject: [CF-metadata] Salinity units
Dear Roy and Alison
The intention of recording the units as 1e-3 (dimensionless) was to suggest
a canonical unit of PSU i.e. approximately the same as parts per thousand.
However, this is unclear and therefore unsatisfactory. We have discussed this
before, in fact, and I believe we have decided in principle that the unit
should be indicated as psu. Since that is not a legal unit in the standard
udunits.dat, in past discussions we have also decided we would publish our
own CF version of udunits.dat, including psu as a unit (not convertible to
other units). The CF udunits.dat should also include sverdrup (=1e6 m3 s-1)
and bel B (hence decibel dB, dimensionless). The latter is already given as
the canonical unit for some standard names, although it is not a legal udunit.
I'd suggest that the CF udunits.dat, with these changes, should be put on our
website, mentioned in 3.1 section about units in the CF standard, and used by
the CF checker.
Best wishes
Jonathan
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Received on Wed Jun 17 2009 - 01:18:48 BST
