Remove unused variables for GFS v17 EE2 compliance

[RussTreadon-NOAA]

The debug build of GSI develop at 93c85e5 on WCOSS2 (Cactus) returned the following warning and remark

• 5724 lines with warning #8889: Explicit declaration of the EXTERNAL attribute is required
• 350 lines with remark #7712: This variable has not been used

This issue is opened to document the removal of unused variables.

[RussTreadon-NOAA]

Work for this issue will begin in RussTreadon-NOAA:feature/remove_unused

[RussTreadon-NOAA]

20251205 update

Given the large number of warning #8889: Explicit declaration of the EXTERNAL attribute is required lines, add noexternals to the -warn line for the debug gsi and enkf compiler flags. This doesn't fix the EXTERNAL warnings ... it simply turns them off.

Many of the unused variables are in subroutine argument lists and declared but not used in the subroutine. Other variables are for code which is commented out. Some variables are clearly not used and have been removed. These changes were committed at eb2b9c0.

After this commit 300 remark #7712: This variable has not been used. remain. The major sources of unused variables are

• 128 unused variables in src/gsi/gsdcloudanalysis4*.F90
• 68 various src/gsi/gsi_*Oper.F90
• 38 src/gsi/stub_pertmod.F90 and src/gsi/stub_ensmod.F90
• 29 src/gsi/setupcldtot.F90
• 15 src/gsi/sfcobsqc.f90

The remaining unused variables are in various source code files with one to four unused variables per file.

Run ctests against develop at 93c85e5 with the following results

Test project /lfs/h2/emc/da/noscrub/russ.treadon/git/gsi/unused/build
    Start 1: global_4denvar
    Start 2: rtma
    Start 3: rrfs_3denvar_rdasens
    Start 4: hafs_4denvar_glbens
    Start 5: hafs_3denvar_hybens
    Start 6: global_enkf
1/6 Test #3: rrfs_3denvar_rdasens .............   Passed  975.89 sec
2/6 Test #5: hafs_3denvar_hybens ..............   Passed  1465.36 sec
3/6 Test #4: hafs_4denvar_glbens ..............   Passed  1824.93 sec
4/6 Test #6: global_enkf ......................   Passed  1847.75 sec
5/6 Test #2: rtma .............................   Passed  1944.56 sec
6/6 Test #1: global_4denvar ...................   Passed  2584.73 sec

100% tests passed, 0 tests failed out of 6

Total Test time (real) = 2584.85 sec

[RussTreadon-NOAA]

@CatherineThomas-NOAA : Two questions

1. What is the deadline for GFS v17 GSI/EnKF software EE2 compliance?
2. Who is tasked to work on ensuring GFS v17 GSI/EnKF software EE2 compliance?

The same questions were posted in GDASApp issue #1579

[CatherineThomas-NOAA]

@RussTreadon-NOAA - Now that we've completed our initial validation of the retro configuration, we're starting to pivot more to EE2 compliance activities.

1. Code delivery is tentatively scheduled for June.
2. We don't have someone officially tasked for this yet, but I'll work with @danholdaway to identify a point person for this.

Copying to NOAA-EMC/GDASApp#1579 for completeness.