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Units and nomenclature in oceano^aphy
Dooley drew the WG's attention to the confusion and uncertainty in the community about units and nomenclature in
connection with salinity and density values. He pointed out that this confusion should be unnecessary as clear advice
was provided some time ago by the lAPSO/SUN group on units (UNESCO, 1985, p 74, UNESCO Technical Papers in
Marine Science, 45, "The International System of Units (SI) in Oceanography) and by JPOTS (UNESCO 1991,
"Processing of Océanographie Station Data"). Both of these groups were co-sponsored by ICES, and ICES is therefore
obligated to ensure that the advice given is heeded.
With regard to salinity it was noted that salinity became a dimensionless unit with the introduction of PSS-78 (Practical
Salinity Scale 1978) . Declaration of units in many published and unpublished texts is however commonplace (e.g.,
PSU, psu, ppt,%o), but it is incorrect to do so. If any description of the given salinity values is required then the values
may be followed by (FSS). Nothing more is necessary, and declaring nothing is to be preferred.
With regard to density, both SUN and JPOTS advise that use of the symbol o must be discontinued since EOS-80
(Equation of State 1980) yield density values in units of kgW rather than the dimensionless quantity of a. The JPOTS
book, ppI6-17, argues as follows:
"Knudsen's equation of state at atmospheric pressure is expressed through the specific gravity anomaly ('sigma-t')