Adding diagnostics to WRF-DART documentation

[braczka]

Description:

Added a more complete diagnostics section to the WRF-DART Tutorial.

Fixes issue

Address issue #543

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Documentation changes needed?

• My change requires a change to the documentation.
  • I have updated the documentation accordingly.

Tests

I used diagnostic output from a WRF Tutorial example I have already run. The
BASEDIR is located here: /glade/scratch/bmraczka/WRF_DART_Tut4. The analysis_increment.nc,
obs_epoch_029.nc and obs_diag_output.nc files, in which I tested the new diagnostic section with
are located in ~/output/2017042712/.

Checklist for merging

• Updated changelog entry
• Documentation updated
• Update conf.py

Checklist for release

• Merge into main
• Create release from the main branch with appropriate tag
• Delete feature-branch

Testing Datasets

• Dataset needed for testing available upon request
• Dataset download instructions included
• No dataset needed

[hkershaw-brown]

note for reviewers, the readthedocs for this pull request can be viewed can be viewed here:
https://dart-documentation--544.org.readthedocs.build/en/544/models/wrf/tutorial/README.html#step-6-diagnosing-the-assimilation-results

[mjs2369]

@braczka this documentation is great. I have a few questions and comments, but overall this could be merged now. Let me know what you think about the following comments and I can go ahead and approve this PR.

It might be useful here to include a link to our documentation page that details the other QC values and their reason for rejection.
"See the 'DART quality control field page' (https://docs.dart.ucar.edu/en/latest/guide/dart-quality-control.html) for more information on the other values for QC and their reason for rejection"

This is more of a question I have personally, but what determines the vertical axis for the different plots? Most of the diagnostic plots use pressure, but this plot uses surface. Is it simply the type of observation and what that type uses as a vertical coordinate that determines this?

In the Quantification of model-observation mismatch and ensemble spread section of the diagnostics, the ensemble statistic total spread is used explicitly (copy = 'totalspread';). Are there other useful ensemble statistics other than total spread that could used for these plot_rmse figures and should be mentioned here?

It may be useful here to give some examples of these modifiable pre-set options.

[braczka]

Latest commits addresses comments by @mjs2369. Also got rid of unrelated and annoying footnote build errors in CLM documentation to partially address issue #546

[mjs2369]

Looks great! Approved.