Hi John,
Defining 'production' as 'production per unit volume' or maybe 'mass created per unit volume per unit time' would seem consistent to me. I'll leave to Jonathan to pick it up if I've got it wrong.
I've never seen a terrestrial production profile and understand that terrestrial measurement protocols tend to give direct measurements per unit area, whereas in the oceans we measure per unit volume to generate profiles that are then integrated to give values per unit area. Hence my comment, but as you're happy to be marine-specific then no problem.
I don't agree with Philip - if you look at all existing productivity codes (mostly mole productivities) then you seem to be following a well-established trend..
I also failed to understand Jonathan's comment concerning an alias - spot measurements and depth-integrated measurements are very different quantities.
Cheers, Roy.
________________________________________
From: CF-metadata [cf-metadata-bounces at cgd.ucar.edu] On Behalf Of John Graybeal [john.graybeal at marinexplore.com]
Sent: 05 June 2013 19:38
To: CF Metadata List
Subject: Re: [CF-metadata] new standard name for primary productivity of carbon per unit volume
Roy, I'm happy to use production instead of productivity, if that's the rule. Should the definition say '"Production" means production per unit volume."?
Jonathan and Roy, adding a reference to sea_water is fine. I could imagine the same metric in a terrestrial experiment, but this item is marine, so if that's the preference I'll go with it. The "mass_concentration" and "moles_per_unit_mass" terms use the expression 'in_sea_water', which seems the right phrase fit to me.
Philip, adding expressed_as_carbon is present in some patterns, but was not present in the names of the two examples I was working from (net/gross_primary_productivity_of_carbon). To this lay person, it indicates the carbon is being ussed as a proxy, at least in part. ("The productivity was actually of 4 substances, but we are measuring the carbon expression only.") Since in this case, the data seemed to be representing actual carbon productivity, and the provider initially chose net_primary_productivity_of_carbon as the appropriate term, I want with that. Of course, I Am Not An Expert, may not understand the nuances, and can not explain why the existing explanation includes this phrasing.
Jonathan, I think it is not an alias (as I understand aliases) of the terms that are per unit area, because the units are different. Do I understand aliases correctly?
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.
John
> From: Jonathan Gregory <j.m.gregory at reading.ac.uk>
> Subject: [CF-metadata] new standard name for primary productivity of carbon per unit volume
> Date: June 5, 2013 7:53:25 AM PDT
> To: <cf-metadata at cgd.ucar.edu>
>
> Dear John
>
> I should think it would be helpful to add per unit volume of *what*? to make
> this clearer.
>
> The existing name could be made an alias of one _per_unit_area if that is
> generally thought to be a good idea.
>
> Besy wishes
>
> Jonathan
> From: "Cameron-smith, Philip" <cameronsmith1 at llnl.gov>
> Subject: Re: [CF-metadata] new standard name for primary productivity of carbon per unit volume
> Date: June 5, 2013 8:11:53 AM PDT
> To: "'john.graybeal at marinexplore.com'" <john.graybeal at marinexplore.com>, "'cf-metadata at cgd.ucar.edu'" <cf-metadata at cgd.ucar.edu>
>
> Hi John,
>
> Would it be appropriate to add _expressed_as_carbon, as indicated in the description (which follows an existing CF pattern)?
>
> Best wishes,
>
> Philip
On Jun 5, 2013, at 07:54, "Lowry, Roy K." <rkl at bodc.ac.uk> wrote:
> Hi John,
>
> I think if you look at the various molar primary productivity standard names you'll see that the decision has been made in the past to define 'productivity' as 'production per unit area'. It might be less confusing if you used
>
> net_primary_production_of_carbon_per_unit_volume
>
> It might also be helpful to constrain this new standard name to the marine environment as production per unit volume doesn't fit the terrestrial domain as well as production per unit area - say something like:
>
> net_primary_production_of_carbon_per_unit_volume_of_sea_water
>
> Cheers, Roy.
>
> Please note that I now work part-time from Tuesday to Thursday. E-mail response on other days is possible but not guaranteed!
>
> -----Original Message-----
> From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of John Graybeal
> Sent: 05 June 2013 03:07
> To: CF Metadata List
> Subject: [CF-metadata] new standard name for primary productivity of carbon per unit volume
>
> I would like to request a CF standard name.
>
> Name: net_primary_productivity_of_carbon_per_unit_volume
> Units: kg m-3 s-1
> Definition: Net primary productivity is the excess of gross_primary_producivity (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). "Productivity of carbon" refers to the production of biomass expressed as the mass of carbon which it contains.
>
> There is an existing net_primary_productivity_of_carbon, expressed per unit area. As we are making a data set available which is integrated over a vertical extent, producing values with units to match (i.e., kg m-3 s-1), a new standard name is needed.
>
> Note: It appears the definition of net primary productivity may assume the value will be measured as per unit area. This probably needs to be corrected.
>
> John
>
>
>
>
>
> ------------------------------------
> John Graybeal
> Senior Data Manager, Metadata and Semantics
>
> T +1 (408) 675-5545
> F +1 (408) 616-1626
> skype: graybealski
>
> Marinexplore
> 920 Stewart Drive
> Sunnyvale, CA
>
>
>
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------------------------------------
John Graybeal
Senior Data Manager, Metadata and Semantics
T +1 (408) 675-5545
F +1 (408) 616-1626
skype: graybealski
Marinexplore
920 Stewart Drive
Sunnyvale, CA
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Received on Wed Jun 05 2013 - 13:32:26 BST
