[CF-metadata] New standard_name values for some cloud and aerosol related variables

From: Jonathan Gregory <j.m.gregory>
Date: Thu, 1 Oct 2015 17:24:04 +0100

Dear Maarten

> There is one issue left: the two wavelengths used in the derivation
> of the 'residue' (older, even more vague name than
> ultraviolet_aerosol_index) must somehow be attached to the variable.
> We can stipulate that the anciliary_variables link to a variable
> with standard_name radiation_wavelength to indicate these two
> wavelengths. I think something similar have been done before.

This too would normally be done by using a coordinate or scalar coordinate
variable; many quantities described by standard names use this mechanism for
attaching defining parameters. I suppose we should put an entry in the FAQ
for this. The difficulty is that you have got two of them. Excuse me for not
having read the reference you supplied: do these two wavelengths describe a
range in any sense, so that it would make sense to store than as bounds for
a size-one coordinate variable? If not, you could do as you suggest (a size-
two coordinate variable) or (perhaps more user-friendly), could the two
defining parameters be given two new standard names containing the phrase
radiation_wavelength, to distinguish the two coordinates?

Reasons for not using attributes include that it avoids proliferation of
attributes to be defined, which make the convention more complicated; that
these parameters often need attributes themselves (particularly units);
that sometimes the parameter might take several possible values, and then
it is obviously like a coordinate variable i.e. an independent variable
on which the data variable depends.

> This fitting is also the result of radiative transfer calculations
> (usually through a lookup table). I have no objection against the
> use of 'effective'.

OK, thanks.

> "assuming_complete_cloud_cover" has my slight preference.
I slightly prefer assuming_completely_cloudy_sky, not on grounds of
English (either sounds fine to me), but because of the correspondence with
assuming_clear_sky. But others may disagree.

Best wishes

Jonathan
Received on Thu Oct 01 2015 - 10:24:04 BST