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 _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
