[CF-metadata] Sea water transparency and reflectance.

From: Jonathan Gregory <j.m.gregory>
Date: Fri, 16 Oct 2009 09:44:12 +0100

Dear Olivier

> surface_reflectance (1)
>
> CF already propose `surface_albedo', so from this basis we propose to
> extend it with a less specific quantity.

We've not defined "albedo" in the existing names. I believe it refers to all
incoming radiation, direct beam or diffuse - is that right? Please could you
suggest how reflectance and albedo are distinguished? Also, what does
reflectivity mean, which is a word used in standard names already (in
connection with radar)? Is it different from reflectance.

> *depth_of_disappearance_from_surface (m)
>
> A quantity that is usually known as Secchi disk depth.
>
> I must admit I am not very satisfied with this proposal because the
> first thing that come into our mind is `depth of disappearance of
> what?'.

Thanks for the references. I think it partly depends on what the intention of
the data variable is. My incomplete understanding of the refs that the Secchi
disk may be a way to estimate the quantity with this existing CF standard name:
  volume_scattering_coefficient_of_radiative_flux_in_sea_water:m-1
Is that right? If so, could the data be converted into that geophysical
quantity and named accordingly? On the other hand, if the intention is to
record the "raw" measurement, then it may be better to be explicit about this
and name it e.g. secchi_depth_of_sea_water, and leave it to the definition to
explain what it is.

Best wishes

Jonathan
Received on Fri Oct 16 2009 - 02:44:12 BST