Hi Paul -
I'm not sure if anyone else is ready to retire salinity as a
standard name meaning 'salinity on the practical salinity
scale'.
Also I still think your proposed definitions are a little too closely
tied to the teos-10 code and to the measurement/calculation
methods. For example, where does remotely sensed surface salinity
fit in? I'm really not sure, but I suspect it's reported on the PSS, but
without a conductivity observable in the "raw" data.
Which reminds me, do you want to add sea_surface_absolute_salinity
to your list?
Personally, I'd go with definitions closer to:
sea_water_salinity: Salt content of seawater on the Practical Salinity
Scale of 1978 (PSS-78), usually based on the electrical conductivity
of seawater.
sea_water_absolute_salinity
Definition: The mass fraction of salts in seawater as defined by the
Thermodynamic Equation Of Seawater - 2010 (TEOS-10), which
includes corrections for spatial variations in the composition of
seawater.
Cheers -
Nan
On 7/6/11 9:45 PM, Paul.Durack at csiro.au wrote:
> Fair point Nan..
>
> We should then do this..
>
> Convert the current "sea_water_salinity" (to be discontinued in its use) to be an alias of the new standard name "sea_water_practical_salinity".
>
> An updated definition for "sea_water_absolute_salinity" following your suggestion is included below, plus a new definition for "sea_water_practical_salinity".
>
> I would recommend each of the new standard names also has an additional copy created, with the prefix "change_over_time_in_*"
>
> ***
> sea_water_conservative_temperature
> Definition: Conservative Temperature is potential enthalpy divided by a fixed value of the specific heat of seawater, namely cp_0 = 3991.86795711963 J kg-1 K-1. Conservative temperature is designed to be as close as possible to potential temperature, but is two orders of magnitude more conservative in the ocean. Because of this, Conservative Temperature can be regarded as being proportional to the heat content of seawater per unit mass.
> Canonical units: K
> Reference: www.teos-10.org
>
> sea_water_absolute_salinity
> Definition: Absolute Salinity, S_A, is the mass fraction of dissolved material in seawater. In fact TEOS-10 estimates Absolute Salinity as the salinity variable that, when used with the TEOS-10 expression for density, yields the correct density of a seawater sample even when the sample is not of Standard Composition. In practice Absolute Salinity is often calculated from Practical Salinity and a value of Absolute Salinity Anomaly which is found using computer software via a global look-up table.
> Canonical units: g kg-1
> Reference: www.teos-10.org
>
> sea_water_practical_salinity
> Definition: Practical Salinity, S_P, is defined on the Practical Salinity Scale of 1978 (PSS-78) and is calculated from the electrical conductivity of seawater (as well as temperature and pressure).
> Canonical units: 1e-3, parts per thousand. Officially S_P is unitless, but often authors use psu, as in S_P = 35 psu.
> Reference: www.teos-10.org
>
> sea_water_preformed_salinity
> Definition: Preformed Salinity is a salinity variable that is designed to be as conservative as possible, by removing the estimated biogeochemical influences on the seawater composition from other forms of salinity.
> Canonical units: g kg-1
> Reference: www.teos-10.org
>
> sea_water_potential_enthalpy
> Definition: Potential enthalpy is the enthalpy of a seawater parcel after an adiabatic and isohaline change in pressure from its in situ pressure to the sea pressure p = 0 dbar.
> Canonical units: J kg-1
> Reference: www.teos-10.org
> ***
>
> So for clarity, the new proposed names are:
>
> sea_water_conservative_temperature
> sea_water_absolute_salinity
> sea_water_practical_salinity
> sea_water_preformed_salinity
> sea_water_potential_enthalpy
> change_over_time_in_sea_water_conservative_temperature
> change_over_time_in_sea_water_absolute_salinity
> change_over_time_in_sea_water_practical_salinity
> change_over_time_in_sea_water_preformed_salinity
> change_over_time_in_sea_water_potential_enthalpy
>
> Cheers,
>
> P
>
> -----Original Message-----
> From: cf-metadata-bounces at cgd.ucar.edu [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Nan Galbraith
> Sent: Thursday, July 07, 2011 3:40 AM
> To: cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] new TEOS-10 standard names
>
> I agree that we probably need these names now. I'd like to
> suggest, though, that the definition of absolute salinity should
> start with the phrase 'mass fraction of salt in seawater', or
> maybe 'concentration of salt in seawater'.
>
> And while we're at it, we should probably consider revising the
> definition of sea_water_salinity; currently all we have is: "The unit
> of salinity is PSU, which is dimensionless. The units attribute
> should be given as 1e-3 or 0.001 i.e. parts per thousand if
> salinity is in PSU."
>
> The units designation implies that we're using practical
> salinity, but the definition should probably be more explicit.
> We could add something like "Salinity ratio on the Practical Salinity
> Scale."
>
> Cheers - Nan
>
>
> On 7/6/11 3:35 AM, Paul.Durack at csiro.au wrote:
>> I'd like to propose a series of new standard names, these names are associated with the recent release of the Thermodynamic Equation Of Seawater 2010 (TEOS-10 - www.teos-10.org).
>>
>> Additional to these names, I would also like to propose the "change_over_time_in_*" prefixes are also created.
>>
>> The proposed new standard names, along with definition, units and reference details are below.
>>
>> ***
>> sea_water_conservative_temperature
>> Definition: Conservative Temperature is potential enthalpy divided by a fixed value of the specific heat of seawater, namely cp_0 = 3991.86795711963 J kg-1 K-1. Conservative temperature is designed to be as close as possible to potential temperature, but is two orders of magnitude more conservative in the ocean. Because of this, Conservative Temperature can be regarded as being proportional to the heat content of seawater per unit mass.
>> Canonical units: K
>> Reference: www.teos-10.org
>>
>> change_over_time_in_sea_water_conservative_temperature
>>
>> sea_water_absolute_salinity
>> Definition: Absolute Salinity is the salinity variable that when used with the TEOS-10 expression for density yields the correct density of a seawater sample even when the sample is not of Standard Composition. In practice Absolute Salinity is often calculated from Practical Salinity and a value of Absolute Salinity Anomaly which is found using computer software via a global look-up table.
>> Canonical units: g kg-1
>> Reference: www.teos-10.org
>>
>> change_over_time_in_sea_water_absolute_salinity
>>
>> sea_water_preformed_salinity
>> Definition: Preformed Salinity is a salinity variable that is designed to be as conservative as possible, by removing the estimated biogeochemical influences on the seawater composition from other forms of salinity.
>> Canonical units: g kg-1
>> Reference: www.teos-10.org
>>
>> change_over_time_in_sea_water_preformed_salinity
>>
>> sea_water_potential_enthalpy
>> Definition: Potential enthalpy is the enthalpy of a seawater parcel after an adiabatic and isohaline change in pressure from its in situ pressure to the sea pressure p = 0 dbar.
>> Canonical units: J kg-1
>> Reference: www.teos-10.org
>>
>> change_over_time_in_sea_water_potential_enthalpy
>> ***
>>
>> Cheers,
>>
>> P
>> _______________________________________________
>> CF-metadata mailing list
>> CF-metadata at cgd.ucar.edu
>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>
>
--
*******************************************************
* Nan Galbraith (508) 289-2444 *
* Upper Ocean Processes Group Mail Stop 29 *
* Woods Hole Oceanographic Institution *
* Woods Hole, MA 02543 *
*******************************************************
Received on Thu Jul 07 2011 - 08:53:04 BST
