Dear Lars I think that using a flag_value would be a good CF way to do this. I am not sure whether it's a good idea to choose a value which is outside the valid range. That's not a problem for CF (that is, it's not prohibited), but maybe it might not suit some software, which could object if it wasn't aware of CF flag_values.
Best wishes Jonathan ----- Forwarded message from Bärring Lars <lars.barr...@smhi.se> ----- > Date: Fri, 19 Jul 2019 10:20:35 +0000 > From: Bärring Lars <lars.barr...@smhi.se> > To: "cf-metadata@cgd.ucar.edu" <cf-metadata@cgd.ucar.edu> > Subject: [CF-metadata] How to encode "not occurring" as distinct from > "missing data" > > Dear all, > > We are considering how best to store data produced by some computation where > there has to be a distinction between missing input data (i.e. no input data > available) and "not occurring" (i.e. input data exists but the computation > did not result in a valid numeric value). > > In practice, the situation is reasonably similar to what was discussed back > in 2017 (in the thread "Recording "day of year on which something happens") > where Jim Biard offered a solution > (http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2017/019238.html). > > We have considered his solution to use flag values outside the valid_range of > the data variable to indicate "no_occurrence". We have also considered to use > a separate quality variable with flag values to use as as a mask (combined > with _MissVal in the data variable). > > In this work the following questions surfaced, > > -- Is there any experience regarding how 'standard software' would handle > either of these alternatives, is one more generally accepted? > > -- Is there any experience to guide us regarding which is better, or > generally more "in line with the CF Conventions"? > > -- Is there another better approach that we have not thought of? > > > Many thanks, > Lars > > _______________________________________________ > CF-metadata mailing list > CF-metadata@cgd.ucar.edu > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata ----- End forwarded message ----- _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
