Data output for seaborn_diag.py

[katjaweigel]

Is your feature request related to a problem? Please describe.
Diagnostic scripts should save the plotted data the work_dir, preferably as .nc file following the contribution guidelines (https://docs.esmvaltool.org/en/latest/community/diagnostic.html#diagnostic-output). This is missing for several diagnostics in the main, including seaborn_diag.py. For this diagnostic it is important to add it soon, because the data are required for the REF in ref/recipe_ref_trend_regions.yml.

Would you be able to help out?
I could try to add the data, similar to _save_boxplot_data in monitor/multi_dataset.py?

[schlunma]

The reason I did not implement this originally is that the output of this diagnostic is kind of arbitrary (arbitrary variables, arbitrary dimensions, etc.). This makes it very hard to implement a general function for this.

I suggest you use iris.pandas.as_cubes for this. I tried this originally and got it working for some cases, but not for all, so I gave up eventually. Maybe it got improved in the meantime.

In any case, please add an option write_netcdf to this diagnostic to be able to disable this feature in case it does not work for cases.

[katjaweigel]

@schlunma thanks for the info! Adding an option to disable it is a good idea.

[schlunma]

One more thought on this: It might also be nice to populate the aux_coord_cols, cell_measure_cols, and ancillary_variable_cols arguments in iris.pandas.as_cubes when the diagnostic is used with the options add_ancillary_variables/add_aux_coords/add_cell_measures.