Dear Karl, All, Apologies for taking a while to look at these names. Yes, there is a difference between the two names subsurface_litter_carbon_content and surface_litter_carbon_content.
Most litter name definitions contain the sentence ' "Litter" is dead plant material in or above the soil' which I think I originally adapted from the "litter carbon" description of these two quite old names. I understand surface_litter_carbon_content to mean the carbon content of litter lying above the soil surface whereas subsurface_litter_carbon_content pertains to litter buried within the soil. The sum of the two would be the quantity with the standard name litter_carbon_content. The definitions of all three names should be updated. Furthermore, they should really be mass_content names like the new ones we have just introduced for C4MIP, e.g. litter_mass_content_of_13C. I suggest we introduce aliases as follows: surface_litter_carbon_content becomes surface_litter_mass_content_of_carbon (kg m-2) ' "Litter" is dead plant material in or above the soil. "Surface litter" means the part of the litter resting above the soil surface. "Content" indicates a quantity per unit area. The sum of the quantities with standard names surface_litter_mass_content_of_carbon and subsurface_litter_mass_content_of_carbon has the standard name litter_mass_content_of_carbon.' subsurface_litter_carbon_content becomes subsurface_litter_mass_content_of_carbon (kg m-2) ' "Litter" is dead plant material in or above the soil. "Subsurface litter" means the part of the litter mixed within the soil below the surface. "Content" indicates a quantity per unit area. The sum of the quantities with standard names surface_litter_mass_content_of_carbon and subsurface_litter_mass_content_of_carbon has the standard name litter_mass_content_of_carbon.' litter_carbon_content becomes litter_mass_content_of_carbon (kg m-2) ' "Litter" is dead plant material in or above the soil. "Content" indicates a quantity per unit area. The sum of the quantities with standard names surface_litter_mass_content_of_carbon and subsurface_litter_mass_content_of_carbon has the standard name litter_mass_content_of_carbon.' Are these okay? While we're looking at these I think we should also update the existing name litter_carbon_flux, defined as ' "Litter carbon" is dead inorganic material in or above the soil quantified as the mass of carbon which it contains. The litter carbon flux is the rate of production of litter. In accordance with common usage in geophysical disciplines, "flux" implies per unit area, called "flux density" in physics.' Fortunately the definition does make it clear that it's a flux into the litter, but the name itself is rather uninformative. Also, if the litter is dead plant material, then presumably the flux is from vegetation to litter. So I'd suggest updating this to be more similar to the new C4MIP names: litter_carbon_flux becomes mass_flux_of _carbon_into_litter_from_vegetation (kg m-2 s-1) ' "Litter" is dead plant material in or above the soil. In accordance with common usage in geophysical disciplines, "flux" implies per unit area, called "flux density" in physics.' That would make this one the sum of Chris's new C4MIP names mass_flux_of_carbon_into_litter_from_vegetation_due_to_mortality and mass_flux_of_carbon_into_litter_from_vegetation_due_to_senescence wouldn't it? Do others agree? Best wishes, Alison ------ Alison Pamment Tel: +44 1235 778065 NCAS/Centre for Environmental Data Archival Email: [email protected] STFC Rutherford Appleton Laboratory R25, 2.22 Harwell Oxford, Didcot, OX11 0QX, U.K. -----Original Message----- From: CF-metadata [mailto:[email protected]] On Behalf Of Karl Taylor Sent: 03 February 2018 06:42 To: [email protected] Subject: [CF-metadata] two standard names for same quantity? I noticed that "subsurface_litter_carbon_content" has the same "definition" as "surface_litter_carbon_content": "Content" indicates a quantity per unit area. "Litter carbon" is dead plant material in or above the soil quantified as the mass of carbon which it contains. The surface called "surface" means the lower boundary of the atmosphere. Is there a difference or are these two names aliases for the same quantity? _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
