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 B?rring Lars <Lars.Barring at smhi.se> -----
> Date: Fri, 19 Jul 2019 10:20:35 +0000
> From: B?rring Lars <Lars.Barring at smhi.se>
> To: "cf-metadata at cgd.ucar.edu" <cf-metadata at 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
>
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----- End forwarded message -----
Received on Fri Jul 19 2019 - 06:57:40 BST
