Source of truth in verification results

[jonasbhend]

Currently, we don't record the truth used to produce verification results. Therefore, if you recompute evaluation with a different truth (e.g. analysis / stations), the intermediate verification files (currently verif.nc and verif_aggregated.nc) will be overwritten. To avoid this, we propose to make intermediate verification results truth-specific. Also, this may open up the possibility to run evaluation experiments with multiple truth data sources in the future.

Summary of changes

• introduce truth (label) in rules producing intermediate verification files
• record truth label and root in NetCDF metadata (convenience)

[clairemerker]

Good extension, thanks! :) The truth label used will be the one already set in the configs, right?

[dnerini]

Thanks! I like this addition, but the approach we used elsewhere is based on hashing the relevant parameters instead of using labels, see also #169

Did you consider doing the same here?