Add WRF hybrid vertical coordinate

braczka commented 4 months ago

Description:

Adds the ability for DART to detect whether WRF is using Hybrid Vertical Coordinate (HVC) or terrain following (TF) system. WRF added this capability starting in WRFv3.9. The DART code automatically identifies the coordinate system by identifying coordinate attribute information within WRF file. Also compatible with pre WRFv3.9 versions which did not include explicit attribute information for vertical coordinate system.

Fixes issue

Fixes issue #649

Types of changes

[x] 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.

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 commented 3 months ago

@braczka is this pull request ready for review?

braczka commented 3 months ago

@braczka is this pull request ready for review?

Not quite yet. I haven't heard anything from Arthur about any testing that his group has done. I have had success testing the sigma hybrid code as part of my comment to the WRF refactor issue here: https://github.com/NCAR/DART/issues/404#issuecomment-2032428709. Things look good (the code worked with WRFv4.0), but I need to do some additional testing with different versions of WRFv3 and 4 that isolate the impact of sigma hybrid coordinate code. I should have this done in less than a week -- Derecho has been down the last couple of days, so I switched off to different tasks.

braczka commented 2 months ago

I tested this sigma hybrid code with the WRF-DART Tutorial example for WRFv4.0 and WRFv4.5.2. I performed a third simulation with WRFv4.5.2, but with no sigma hybrid fix. All three cases can be found here: /glade/derecho/scratch/bmraczka/WRF_DART_Tutorial /glade/derecho/scratch/bmraczka/WRFv4.5_DART_Tutorial /glade/derecho/scratch/bmraczka/WRFv4.5_DART_nohybrid

When including the sigma hybrid code the performance of WRFv4.5.2 appears very similar to WRFv3.9.1, based on standard tutorial statistics. For example WRF3.9.1 (left) and WRFv4.5.2 (right)

Screen Shot 2024-04-16 at 5 34 59 PM

Also of note is that if WRFv4.5.2 is run without the hybrid fix, the assimilation doesn't fail outright -- the performance is just deprecated as shown below (WRFv4.5.2 w/o hybrid fix on left, WRFv4.5.2 with hybrid fix on right)

Screen Shot 2024-04-16 at 5 39 35 PM

This means a WRFv4+ DART user could easily perform an assimilation without the hybrid fix and not realize the performance is deprecated. In terms of the fix itself, however, it looks good to go.

NCAR / DART