Copilot reviewed 5 out of 8 changed files in this pull request and generated no comments.

file_list = [f'"{remove_quotes(item)}"' if ' ' in item else item for item in file_list]

self.config.set('config', 'RDP_SKIP_RUN_CHECK', True)

if 'OBS_POINT_STAT_INPUT_TEMPLATE' in config_overrides and 'PYTHON' in config_overrides['OBS_POINT_STAT_INPUT_TEMPLATE']:

George, thanks for pointing out the differences that this PR causes. I definitely do think that we should add set_attr options to eliminate the diffs in the stat files and reduce the ones in the NetCDF files. The "truth" units (%) are better than the new "output" units (1). And if we're updating the units, we may as well update the level string as well. And this will serve as a nice example of the -set_attr options in a METplus Use Case.

I'd recommend adding:

FCST_VAR1_OPTIONS = -set_attr_units % -set_attr_level Z0

I'll just proposed that one line change to the code.

Thanks @georgemccabe for adding the set_attr_units and set_attr_level options to minimize the diffs. The remaining differences for the WRF-Fire Grid-Stat runs are in the NetCDF matched pairs files:

• The long_name variable attributes are modified but that's totally fine since the content for that is now being read directly from the input files.
• The grid definition information listed in the global attributes are modified slightly, generally in the second decimal place, but so too have the x_pin and y_pin locations.

You suggested that these were minor diffs based on rounding, but I think they're actually significant differences. But those differences are actually fine. They are just two different ways of defining the same grid!

The x/y pin locations define the location of the reference lat/lon in the grid. The old x/y of (0,0) means that lat/lon (37.402645, -107.881439) occurs at the lower-left corner of the grid. The new x/y of (235.5, 235.5) means that lat/lon (37.461014, -107.80799) occurs at the center of the grid.

The lat/lon difference from old to new reference location is (-0.058369, 0.073449). Very roughly assuming 110km per degree latitude, with d_km = 0.027542 a shift of 235.5 grid points in the x/y directions = 6.486 km = 0.05896 degrees of latitude... which is very close to the actual latitude difference we're seeing!

So the lat/lon locations have changed very slightly in a way that's consistent with the x/y pin location change... for a very, very tiny grid.

The we're running Grid-Stat with forecast data defined relative to the center of the grid and "observation" data (output from Gen-Vx-Mask) defined relative to the lower-left corner of the grid. Since those grid definitions differ, Grid-Stat needs to put them on a common grid. And in metplus_final.conf I see we're auto-regridding to the forecast grid:

GRID_STAT_REGRID_TO_GRID = FCST

And with nothing overriding the default regridding method in the default Grid-Stat config file, we're regridding using the nearest neighbor method. So the "obs" input data is being regridded with nearest neighbor to forecast grid. But since they're in the same location on earth, we end up getting exactly the same contingency table counts and statistics.

This is a pretty subtle difference. I'd say your options are:

1. Keep everything as-is and let Grid-Stat keep doing its regridding between two grids that are equivalent but defined with different parameters.
2. Modify the Python embedding script used when running Gen-Vx-Mask so that the forecast and observation grids are defined the same way for Grid-Stat.

Honestly, either approach is totally fine. And sticking with the existing "auto-regridding" does demonstrate the functionality of grid handling in MET.

I approve of these changes, but I added a bunch of details and ended with a question in this PR comment. Feel free to stick with the changes as-is or tweak the observation grid definition to avoid unnecessary regridding. Either way is totally fine.