Describe the Problem

This issue was raised in the third topic of the dtcenter/METplus#2312 discussion. Please see this comment for details.

Expected Behavior

While the sample NetCDF file follows the CF-convention, MET is not handling it properly. There are 2 issues to be addressed.

1. The projection x and y dimensions are not defined by coordinate variables, but are identified using the expected standard_name attribute:

	float xgrid(x) ;
		xgrid:standard_name = "projection_x_coordinate" ;
	float ygrid(y) ;
		ygrid:standard_name = "projection_y_coordinate" ;

Renaming to use coordinate variables x(x) and y(y) does enable MET to continue on to the next problem, described below. The task is to inspect the CF-conventions to determine whether or not the use of coordinate variables is required here. If not, generalize the code to inspect all 1-d variables rather than just coordinate variables.

2. MET does not properly parse the polar stereographic grid definition from these files. See below.

Environment

Describe your runtime environment:
1. Machine: Mac Laptop
2. OS: MacOS
3. Software version number(s): Tested using the main_v11.1 branch of MET

To Reproduce

Describe the steps to reproduce the behavior:
1. Download this file:
seaice_conc_monthly_sh_202208_f17_v04r00.nc.gz
2. Rename to coordinate variables:

ncrename -v xgrid,x -v ygrid,y \
seaice_conc_monthly_sh_202208_f17_v04r00.nc \
seaice_conc_monthly_sh_202208_f17_v04r00_MOD.nc

3. Run plot_data_plane at verbosity level 4:

MET-main_v11.1/bin/plot_data_plane \
seaice_conc_monthly_sh_202208_f17_v04r00_MOD.nc plot.ps \
'name="cdr_seaice_conc_monthly"; level="(0,*,*)";' -v 4
...
DEBUG 4: Grid information:
DEBUG 4:    Projection: Stereographic
DEBUG 4:    Nx: 316
DEBUG 4:    Ny: 332
DEBUG 4:    IsNorthHemisphere: false
DEBUG 4:    Lon_orient: -180.000
DEBUG 4:    Bx: nan
DEBUG 4:    By: nan
DEBUG 4:    Alpha: inf

The Bx, By, and Alpha values all have problems.

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