Dear John and Roy,
I think, then, that we are agreed the name should be:
net_primary_production_of_biomass_expressed_as_carbon_per_unit_volume_in_sea_water (kg m-3).
Sorry if I wasn't clear about the definitions. John is correct that we need to distinguish between "productivity" and "production" because they have different implications for the units. "Productivity" has long been defined in standard names as meaning "production per unit area" which implies units of m-2. I am not suggesting any change to this. The quantity of "production", for example, in existing names such as tendency_of_mole_concentration_of_particulate_organic_matter_expressed_as_carbon_in_sea_water_due_to_net_primary_production_by_diatoms, has not in fact been used to specify "per unit volume". It implies only that a quantity of biomass carbon is being produced; the quantity itself may be measured as mass in kg or amount of substance in moles. The "m-3" in the existing names comes from the definition of mole concentration: ' "Mole concentration" means number of moles per unit volume'.
The upshot of this is that we do need different wording for the definitions of production and productivity names. Production names would contain the following:
' "Production of carbon" refers to the production of biomass expressed as the mass of carbon which it contains. Net primary production is the
excess of gross primary production (rate of synthesis of biomass from inorganic precursors) by autotrophs ("producers"), for example, photosynthesis in plants or phytoplankton, over the rate at which the autotrophs themselves respire some of this biomass.'
For productivity names we would add an additional explanatory sentence (as already used in standard names definitions):
' "Production of carbon" refers to the production of biomass expressed as the mass of carbon which it contains. Net primary production is the
excess of gross primary production (rate of synthesis of biomass from inorganic precursors) by autotrophs ("producers"), for example, photosynthesis in plants or phytoplankton, over the rate at which the autotrophs themselves respire some of this biomass. "Productivity" means production per unit area.'
All mention of "per unit mass" or "per unit volume" is then removed from the definition of production itself, which I think it should be. Also, these definitions would allow standard wording regardless of whether the production is land or ocean based, which was my original intention. I would need to go through the eleven existing names to make sure their definitions all follow one or other of the above templates.
For John's new name we can certainly add some extra explanation to the definition as to how the parameter might be used. Based on Roy's explanation I suggest the following:
' In the oceans it is usual to measure carbon production per unit volume at a number of depths for a given horizontal location. The quantity can then be integrated to calculate production per unit area at that location. Standard names for production per unit area use the term "productivity".'
This would be appended to the earlier text about production.
All OK? If so, I will include these changes in the next standard name table update which is currently in preparation, hopefully to be published this week.
Best wishes,
Alison
------
Alison Pamment Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre Email: alison.pamment at stfc.ac.uk
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.
> -----Original Message-----
> From: John Graybeal [mailto:john.graybeal at marinexplore.com]
> Sent: 04 November 2013 22:54
> To: Lowry, Roy K.
> Cc: Pamment, Alison (STFC,RAL,RALSP); cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] new standard name for primary production of
> carbon per unit volume
>
> Hi Roy,
>
> The indication I had received from other sources (when I asked them why CF
> didn't seem to have any production per unit volume names that I could find)
> was that this parameter was generally measured only at the ocean surface,
> via satellites -- hence per unit area was the common unit. Your explanation
> adds a lot to my understanding -- and maybe should be reflected in the
> descriptions!
>
> Thanks!
>
> John
>
> On Nov 4, 2013, at 14:18, "Lowry, Roy K." <rkl at bodc.ac.uk> wrote:
>
> > Hi John,
> >
> > Production per unit volume is the usual parameter measured in the
> oceans. What is usually done is to measure this at maybe half a dozen
> depths at a given position between the surface and 100m and then there is
> an integration procedure that can be done on this dataset to produce a
> single value of production per unit area for that position - I guess with the
> objective of making oceanographic data compatible with terrestrial for
> global aggregates.
> >
> > The tow oceanographic parameters have different dimensionality and
> therefore need to be described by different standard names.
> >
> > Cheers, Roy.
> >
> > ________________________________________
> > From: CF-metadata [cf-metadata-bounces at cgd.ucar.edu] On Behalf Of
> John Graybeal [john.graybeal at marinexplore.com]
> > Sent: 04 November 2013 15:55
> > To: alison.pamment at stfc.ac.uk
> > Cc: cf-metadata at cgd.ucar.edu
> > Subject: Re: [CF-metadata] new standard name for primary production of
> carbon per unit volume
> >
> > Hi Alison,
> >
> > First change is fine by me.
> >
> > Second change is fine for _my_ request. I note that most terms to date
> (and all terrestrial terms?) consider productivity per unit area; mine is the
> first, or one of the first, that is per unit volume. (The difference is reflected
> in the units.) The definition of "net primary production" needs to either be
> written generically (e.g., "per unit area or volume according to the units"),
> or we'll need two different concepts. (I vaguely recall a notion that
> productivity could be by unit area and production by unit volume, but have
> no personal expertise.)
> >
> > John
> >
> >
> > On Nov 4, 2013, at 01:33, alison.pamment at stfc.ac.uk wrote:
> >
> >> Dear John G.,
> >>
> >> Some time ago you proposed a standard name
> net_primary_production_of_carbon_per_unit_volume_in_sea_water with
> canonical units of kg m-3 s-1.
> >>
> >> The proposal is certainly consistent with the syntax of existing
> productivity_of_carbon names. However, there ensued some discussion as
> to whether production|productivity_of_carbon means the same as
> production|productivity_of_biomass_expressed_as_carbon. I think the
> answer to this question is actually 'yes'. The definitions even say '
> "Production of carbon" refers to the production of biomass expressed as the
> mass of carbon which it contains.' I think we need to be careful to retain the
> terms "productivity" or "production" of carbon as part of the names because
> these are the terms widely used and understood by the land surface
> modellers and ocean biogeochemists. However, in the interests of making
> standard names as standard as possible, I suggest that we should in fact
> insert "expressed_as". For example,
> net_primary_mole_productivity_of_carbon_by_diatoms would become
> net_primary_mole_productivity_of_biomass_expressed_as_carbon_by_diat
> oms and your proposed name would be
> > co
> >> me
> net_primary_production_of_biomass_expressed_as_carbon_per_unit_volu
> me_in_sea_water. The change would affect eleven existing names. Would
> that be acceptable? Does anyone else object to the change?
> >>
> >> Regarding the definition of the proposed name, I see that you have tried
> to make it consistent with existing net_primary_productivity names.
> Looking through the standard name table I have found that we have two
> versions of the wording that have been tailored to land based or ocean
> based photosynthesis, respectively. See, for example, the definition of
> net_primary_mole_productivity_of_carbon_by_diatoms versus that of
> net_primary_productivity_of_carbon_accumulated_in_leaves. I think it
> would be better to settle on a single wording for all
> net_primary_production/productivity names, regardless of where the
> process is taking place, so I suggest the following:
> >> " "Production of carbon" refers to the production of biomass expressed
> as the mass of carbon which it contains. Net primary production is the
> excess of gross primary production (rate of synthesis of biomass per unit
> volume from inorganic precursors) by autotrophs ("producers"), for
> example, photosynthesis in plants or phytoplankton, over the rate at which
> the autotrophs themselves respire some of this biomass. "
> >>
> >> Is this OK? If so, I will amend the definitions of the existing names to all
> have consistent wording.
> >>
> >> Thanks for your patience,
> >> Alison
> >>
> >> ------
> >> Alison Pamment Tel: +44 1235 778065
> >> NCAS/British Atmospheric Data Centre Email:
> alison.pamment at stfc.ac.uk
> >> STFC Rutherford Appleton Laboratory
> >> R25, 2.22
> >> Harwell Oxford, Didcot, OX11 0QX, U.K.
> >>
> >>
> >>> -----Original Message-----
> >>> From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On
> Behalf
> >>> Of John Graybeal
> >>> Sent: 02 July 2013 22:56
> >>> To: CF Metadata List
> >>> Subject: Re: [CF-metadata] new standard name for primary production
> of
> >>> carbon per unit volume
> >>>
> >>> As of June 5 this revised name was requested to go with the previously
> >>> submitted definition:
> >>>
> >>> On Jun 5, 2013, at 11:38, John Graybeal <graybeal at marinexplore.com>
> >>> wrote:
> >>>> So I think we have the replacement name of
> >>>> net_primary_production_of_carbon_per_unit_volume_in_sea_water
> >>>> pending further thoughts and responses.
> >>>
> >>> There has been some discussion (thank you), but to my knowledge, no
> >>> outstanding requests for changes since that posting.
> >>>
> >>> In the definition below, I've modified bits of that definition to match
> the
> >>> new term (production). Is this request approvable at this point?
> >>>
> >>> Name:
> net_primary_production_of_carbon_per_unit_volume_in_sea_water
> >>> Units: kg m-3 s-1
> >>> Definition: Net primary production is the excess of gross primary
> production
> >>> (rate of synthesis of biomass per unit volume from inorganic precursors
> by
> >>> autotrophs, or "producers", especially by photosynthesising plants using
> >>> sunlight for energy) over the rate at which they themselves respire
> some of
> >>> this biomass (plant_respiration, assuming all producers to be plants).
> >>> "Production of carbon" refers to the production of biomass expressed as
> the
> >>> mass of carbon which it contains.
> >>>
> >>> John
> >>>
> >>> ------------------------------------
> >>> John Graybeal
> >>> Senior Data Manager, Metadata and Semantics
> >>>
> >>> Marinexplore
> >>> 920 Stewart Drive
> >>> Sunnyvale, CA
> >>>
> >>>
> >>>
> >>> _______________________________________________
> >>> CF-metadata mailing list
> >>> CF-metadata at cgd.ucar.edu
> >>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
> >> --
>
--
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Received on Tue Nov 05 2013 - 05:48:09 GMT
