A couple of questions...
1) Regarding the request to add Chlorophyll_a fluorescence, the proposed
unit is kg/m3, but shouldn't fluorescence have radiation units (i.e.
Watts/m2)? I was not aware that any of the proposed CMIP models treated
fluorescence explicitly, but if that were the case, it would seem like
converting to chlorophyll_a volumetric mass units would seem to me
redundant with the existing chlorophyll_a metric.
2) Regarding the request to add a variable for alkalinity in mass units to
augment the current one volumetric units, this would seem redundant for
models using the Boussinesq Assumption and thus a single reference
density. For non-Boussinesq models, one should be able to approximate this
with sea_water_potential_density (rhopoto), but I acknowledge that this
would make the global integral not exact... Are non-Boussinesq models being
planned? If so, adding alkalinity as a mass-based variable would also then
beg the question as to which tracers should be posted in both units (e.g.
DIC) - how much is the request expected to be expanded?
Cheers, John
On Mon, Dec 5, 2016 at 3:38 AM, Elodie Fernandez <
elodie.fernandez at mercator-ocean.fr> wrote:
> Dear all,
>
> We would like to suggest the addition of two new standard_names for ocean
> biogeochemistry:
>
> - *mass_concentration_of_chlorophyll_a_fluorescence_in_sea_water*
> unit: kg m-3
> definition:
> Mass concentration means mass per unit volume and is used in the
> construction mass_concentration_of_X_in_Y, where X is a material
> constituent of Y. A chemical species denoted by X may be described by a
> single term such as 'nitrogen' or a phrase such as
> 'nox_expressed_as_nitrogen'. Chloropyll fluorescence is a proxy for
> Chlorophyll concentration measuring re-emitted light from light absorption.
> Chlorophylls are the green pigments found in most plants, algae and
> cyanobacteria; their presence is essential for photosynthesis to take
> place. There are several different forms of chlorophyll that occur
> naturally. All contain a chlorin ring (chemical formula C20H16N4) which
> gives the green pigment and a side chain whose structure varies. The
> naturally occurring forms of chlorophyll contain between 35 and 55 carbon
> atoms.Chlorophyll fluorescence is mainly emitted from the Chlorophyll a
> pigment.
>
> I believe there are no standard_names yet for fluorescence. The definition
> was built from the mass_concentration_of_chlorophyll_a_in_sea_water
> definition.
>
> - *sea_water_alkalinity_per_unit_mass*
> unit: mol kg-1
> definition:
> sea_water_alkalinity_per_unit_mass is the total alkalinity (including
> carbonate, nitrogen, silicate, and borate components).
>
> A standard name already exists for alkalinity expressed as mol/m3,
> sea_water_alkalinity_expressed_as_mole_equivalent, but none exist for
> mol/kg.
>
> Best regards,
> Elodie
>
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>
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