Hello Jonathan,
One change I would recommend is to change composition terms such as 'composition_ratio_of_silicon_30_to_silicon_28_in_sinking_flux' to 'composition_ratio_of_silicon_30_to_silicon_28_in_suspended_matter'. The reason for this is that the particles in the water can be collected in several different ways - sediment trapping, stand-alone pumps, filtration of water samples and continuous centrifugation are the ones that instantly spring to mind. The description 'sinking_flux' is only strictly true for the first of these, whereas 'suspended_matter' applies equally to all of them.
Also, is it OK for the fact that the suspended matter is in sea water to be implicit? The term could be confused with atmospheric aerosols or particulates. If not, we need 'in_suspended_matter_in_sea_water'.
Cheers, Roy.
________________________________________
From: CF-metadata [cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Jonathan Gregory [j.m.gregory at reading.ac.uk]
Sent: 13 October 2013 09:33
To: cf-metadata at cgd.ucar.edu
Subject: Re: [CF-metadata] standard names for sediment trap data
Dear Matthias et al.
Thanks for the proposals. I don't know much about this subject. From a CF
point of view, I'd like to follow up various comments that have been made.
As Roy says, CF doesn't decide what quantities should be used; its role is to
agree names for quantities that are used in practice. Thus, we need names for
both mole_flux and mass_flux in this case (quantities with different canonical
units always have distinct standard names), and for biogenic, lithogenic or
unspecified, according to what is needed. Like Tom, I think "total" does not
need to be included. The problem with "total" is that it's a word whose
meaning depends on the comparison with "partial" quantities i.e. it's a
relative term, rather than an absolute one. Potential users might have
different ideas about what's included in "total" so it's best not to use that
word, or if necessary to spell out explicitly what is included.
If isotopic composition needs to be specified, I would prefer phrases like
the one Philip suggested
(composition_ratio_of_silicon_30_to_silicon_28_in_sinking_flux).
The three downward_mass_flux names in the standard name table are for carbon
dioxide in air. The idea in mind is that CO2 is a passive tracer, advected as
a constituent of air. The seven sinking names are for particles in sea water -
I'm guessing that the calcite and aragonite refer to solid matter i.e. shells
- is that right? I guess the idea is that sinking is a process. These are
passive constituents too, but their weight is responsible for their downward
motion; this gets near to the point that Philip made, about the reference
frame. The distinction is natural, but I'm not convinced that we would like to
maintain it, and I think downward would be preferable to sinking. For
instance, what would you choose for the flux of dissolved constituents, such
as oxygen or salt? It wouldn't be natural to call those "sinking". If it is
important to convey the idea of sinking, I suggest it would be better to say
downward_mass/mole_flux_of_X_in_sea_water_due_to_sinking, but I'm sure others
have better informed opinions on this.
Best wishes
Jonathan
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Received on Sun Oct 13 2013 - 02:43:55 BST
