[CF-metadata] One new standard name for OMIP

From: alison.pamment at stfc.ac.uk <alison.pamment>
Date: Mon, 19 Mar 2018 13:09:12 +0000

Dear All,

In 2017 we introduced quite a number of new standard names for the CMIP6 OMIP project. I have been informed that one name is missing from the list of required terms:
square_of_sea_surface_salinity (canonical units: 1e-6)
'The phrase "square_of_X" means X*X. Sea surface salinity is the salt concentration of sea water close to the sea surface, often on the Practical Salinity Scale of 1978. However, the unqualified term 'salinity' is generic and does not necessarily imply any particular method of calculation. The units of salinity are dimensionless and the units attribute should normally be given as 1e-3 or 0.001 i.e. parts per thousand. Sea surface salinity is often abbreviated as "SSS". For the salinity of sea water at a particular depth or layer, a data variable of "sea_water_salinity" or one of the more precisely defined salinities should be used with a vertical coordinate axis. There are standard names for the precisely defined salinity quantities: sea_water_knudsen_salinity, S_K (used for salinity observations between 1901 and 1966), sea_water_cox_salinity, S_C (used for salinity observations between 1967 and 1977), sea_water_practical_salinity, S_P (used for salinity observations from 1978 to the present day), sea_water_
absolute_salinity, S_A, sea_water_preformed_salinity, S_*, and sea_water_reference_salinity. Practical Salinity is reported on the Practical Salinity Scale of 1978 (PSS-78), and is usually based on the electrical conductivity of sea water in observations since the 1960s. Conversion of data between the observed scales follows: S_P = (S_K - 0.03) * (1.80655 / 1.805) and S_P = S_C, however the accuracy of the latter is dependent on whether chlorinity or conductivity was used to determine the S_C value, with this inconsistency driving the development of PSS-78. The more precise standard names should be used where appropriate for both modelled and observed salinities. In particular, the use of sea_water_salinity to describe salinity observations made from 1978 onwards is now deprecated in favor of the term sea_water_practical_salinity which is the salinity quantity stored by national data centers for post-1978 observations. The only exception to this is where the observed salinities are definitely known not to be
 recorded on the Practical Salinity Scale. The unit "parts per thousand" was used for sea_water_knudsen_salinity and sea_water_cox_salinity.'

This name and definition are closely related to the existing name sea_surface_salinity. I think this name looks fine and is unlikely to prompt discussion. Unless any objections are received within the next seven days, this name will be accepted for inclusion in the standard name table and added in the April update.

Best wishes,
Alison

------
Alison Pamment Tel: +44 1235 778065
NCAS/Centre for Environmental Data Archival Email: alison.pamment at stfc.ac.uk
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.
Received on Mon Mar 19 2018 - 07:09:12 GMT