Dear Martin
> The discussion of a machine-readable document with details of rules related to specific standard names is here: https://cf-trac.llnl.gov/trac/ticket/153 . It has been quiet for some time. The dB issues could be covered there, as you say. There is a difference in that the rules discussed in ticket 153 are about specifying what needs to be in the data file, so that it is possible to check that file meta-data is as complete as intended by the convention. Your suggestion would entail adding information that would not be in the data file.
Yes, I agree, that's a bit different. The rules file would provide the info.
It's a convenient place to put it.
> You also suggest that alternative reference levels could be specified in an attribute, but that does not appear to be allowed by current standard name definitions,
I admit that I didn't check the definitions of these standard names! But there
are standard names which refer to a value with a default that can be overridden
by a coordinate variable or scalar coordinate variable (not an attribute). If
there is a use-case for different reference values for any of the dB instances
you mention, we should provide for it using that mechanism by amending the
definitions of the standard names, I suggest.
> It is true that dB is dimensionless, like "1", but we would create huge confusion if dB data values were multiplied by 100 and presented as "%" ... a sound_intensity_level_in_water with a value of 25% might be technically equivalent to 0.25dB, but not very useful to users. I'm not sure how to deal with this, but I'm not comfortable with the idea that dB is fully equivalent to "1" as a unit.
I find that in my version of udunits, bel and decibel are units, and they are
not convertible to dimensionless numbers. I think that's consistent with what
you say and I agree it makes sense like that.
Best wishes
Jonathan
Received on Mon Nov 05 2018 - 14:00:25 GMT
