Hi Matthias,
I like your proposed canonical units and terms. The names are also systematic and clear. I do not see the need to include the word total when an elemental flux is not split into molecular or other components. Items that I think might need further consideration:
1. In the list of XXX items, would it be clearer to specify silicon rather than silica for all terms related to silica (since the molecular composition of lithogenic, biogenic silica forms are often unknown)? Or do we have to write XXX as '_biogenic_silica_as_silicon'
2. Is it worth settling on a standard approach to isotopic (and other) compositions ? For example, 13C-POC. Units of flux rather than composition would be somewhat unusual for isotopes, making variables starting with 'sinking_mass_flux' somewhat odd. That is unfortunate, since indicating sinking flux as the overall sample type seems to be the top category worth retaining. One way around this would be a slight reordering to two groups of variables, e.g.:
sinking_flux_mass_lithogenic_silicon
sinking_flux_composition_lithogenic_silicon_isotopic_ratio_30_28
Or is that clumsy?
Of course we could force all compositional information (isotopes, diatom species relative abundances, etc. )into mass flux units, with satisfyingly simple units, but then they all have to be reconverted into units people want to use. This would mean carrying absolute isotopic abundance for standards within the files for completeness.
As usual there are many ways to skin a cat, but none are easy when the cat sees you coming!
Best wishes,
Tom
On 10/10/2013, at 10:16, "Matthias Lankhorst" <mlankhorst at ucsd.edu> wrote:
Dear CF community,
in the OceanSITES project, we would like to publish data from sediment traps
in files, using the CF conventions. Sediment traps are devices moored
underwater in the ocean, which collect sinking particles (detritus) in a
funnel and into sample bottles for later analyses. Analyses can be done for a
variety of substances. It looks like we need a few more standard names for
these, and possibly a discussion whether some of them should be expressed as
mass fluxes or as substance amount (mole) fluxes.
I noticed that CF already has these standard names, all as mole fluxes with
canonical units of mol m-2 s-1:
sinking_mole_flux_of_aragonite_expressed_as_carbon_in_sea_water
sinking_mole_flux_of_calcite_expressed_as_carbon_in_sea_water
sinking_mole_flux_of_particulate_iron_in_sea_water
sinking_mole_flux_of_particulate_organic_matter_expressed_as_carbon_in_sea_water
sinking_mole_flux_of_particulate_organic_nitrogen_in_sea_water
sinking_mole_flux_of_particulate_organic_phosphorus_in_sea_water
sinking_mole_flux_of_particulate_silicon_in_sea_water
Here is the list of quantities that we need to address in OceanSITES. My
initial proposal is to introduce them all as mass fluxes with canonical units
of kg m-2 s-1. If we should rather go with mole fluxes like the ones above,
please chime in.
Total/organic mass:
Propose new standard names:
sinking_mass_flux_of_particulate_matter_in_sea_water
sinking_mass_flux_of_particulate_organic_matter_in_sea_water
(I suppose these are understood as dry mass, i.e. weighed after water has
evaporated.)
Particulate organic, inorganic, total carbon:
Propose new standard names:
sinking_mass_flux_of_particulate_organic_carbon_in_sea_water
sinking_mass_flux_of_particulate_inorganic_carbon_in_sea_water
sinking_mass_flux_of_particulate_carbon_in_sea_water
(or should we include "total" somewhere in the latter?)
Particulate organic, inorganic, total nitrogen:
Propose new standard names:
sinking_mass_flux_of_particulate_organic_nitrogen_in_sea_water
sinking_mass_flux_of_particulate_inorganic_nitrogen_in_sea_water
sinking_mass_flux_of_particulate_nitrogen_in_sea_water
(or should we include "total" somewhere in the latter?)
Other particulate substances from a list:
Propose new standard names for each of the following, to be constructed as:
sinking_mass_flux_of_particulate_XXX_in_sea_water,
where XXX is:
- aluminum
- iron
- phosphorous
- silica
- biogenic_silica
- lithogenic_silica
- calcium
- titanium
- manganese
- barium
- magnesium
Your expert comments are highly appreciated!
Respectfully, Matthias
--
_______________________________________
Dr. Matthias Lankhorst
Scripps Institution of Oceanography
9500 Gilman Drive, Mail Code 0230
La Jolla, CA 92093-0230
USA
Phone: +1 858 822 5013
Fax: +1 858 534 9820
E-Mail: mlankhorst at ucsd.edu
http://www-pord.ucsd.edu/~mlankhorst/
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Received on Thu Oct 10 2013 - 03:28:08 BST
