Fix the MET library code to correctly parse timing information from Grid-Stat NetCDF matched pairs output files.

[JohnHalleyGotway]

Describe the Problem

This issue arose via GitHub discussions in dtcenter/METplus#1400. The MET library code is not correctly parsing the timing information from the NetCDF matched pairs output files generated by Grid-Stat. While the valid time is consistently correct, the initialization and lead times are not.

Recommend reviewing and revising the MET NetCDF library code logic.

Expected Behavior

The MET tools should parsing timing information from each variable which matches the timing information visible by running ncdump -h.

Environment

Describe your runtime environment:
1. Machine: First found on Linux but repeated on a Mac laptop
2. OS: (e.g. RedHat Linux, MacOS)
3. Software version number(s): identified with MET version 10.0.0 as well as the latest version of the develop branch

To Reproduce

Describe the steps to reproduce the behavior:
1. Use a NetCDF matched pairs file generated by running "make test" to demonstrate
2. Do a NetCDF header dump to see the forecast variable timing info:

ncdump -h out/grid_stat/grid_stat_120000L_20050807_120000V_pairs.nc 

3. Note this timing info:

                FCST_TMP_Z2_DTC165:init_time = "20050807_000000" ;
                FCST_TMP_Z2_DTC165:init_time_ut = "1123372800" ;
                FCST_TMP_Z2_DTC165:valid_time = "20050807_120000" ;
                FCST_TMP_Z2_DTC165:valid_time_ut = "1123416000" ;

4. Plot this variable with plot_data_plane and -v 4:

plot_data_plane out/grid_stat/grid_stat_120000L_20050807_120000V_pairs.nc fcst.ps 'name="FCST_TMP_Z2_DTC165"; level="(*,*)";' -v 4

5. Note that the timing info DOES NOT match the header dump above. The init and lead times are wrong:

DEBUG 4:      valid time: 20050807_120000
DEBUG 4:       lead time: 000000
DEBUG 4:       init time: 20050807_120000

Relevant Deadlines

Fix for MET version 10.1.0. Ideally, also provide a bugfix for 10.0.0 in the main_v10.0 branch.

Funding Source

2792541 and 2702691

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Define Related Issue(s)

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• METplus, MET, METdatadb, METviewer, METexpress, METcalcpy, METplotpy

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[JohnHalleyGotway]

Currently, the MetNcFile class defined in met_file.h defines a single Init and Valid time for each file:

         //
         //  time
         //

      unixtime ValidTime;

      unixtime InitTime;

      int      lead_time () const;   //  seconds

And these values are set on lines 302/303 of met_file.cc when reading each variable. So the timing info for the variable that is read LAST will be used for all variables in the file. And that's the bug.

Recommend removing InitTime, ValidTiem, and lead_time() from the MetNc
File class. Recommend adding them to the NcVarInfo class in nc_var_info.h instead (e.g. AccumTime is already there!).

[JohnHalleyGotway]

@jprestop when this issue is complete and merged into develop, please update METplus Discussion dtcenter/METplus#1400 to let Mallory know. And then you can mark that discussion as being answered and lock it.