[aqm_dev] Fix NEXUS error of GFS files not found when MERRA2 is used

[lwcugb]

DESCRIPTION OF CHANGES:

Type of change

• [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)
• [ ] This change requires a documentation update

TESTS CONDUCTED:

• [ ] hera.intel
• [ X] orion.intel
• [ ] hercules.intel
• [ ] cheyenne.intel
• [ ] cheyenne.gnu
• [ ] derecho.intel
• [ ] gaea.intel
• [ ] gaeac5.intel
• [ ] jet.intel
• [ ] wcoss2.intel
• [ ] NOAA Cloud (indicate which platform)
• [ ] Jenkins
• [ ] fundamental test suite
• [ ] comprehensive tests (specify which if a subset was used)

DEPENDENCIES:

DOCUMENTATION:

ISSUE:

CHECKLIST

• [ ] My code follows the style guidelines in the Contributor's Guide
• [ ] I have performed a self-review of my own code using the Code Reviewer's Guide
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] My changes need updates to the documentation. I have made corresponding changes to the documentation
• [X ] My changes do not require updates to the documentation (explain).
• [ ] My changes generate no new warnings
• [ ] New and existing tests pass with my changes
• [ ] Any dependent changes have been merged and published

LABELS (optional):

A Code Manager needs to add the following labels to this PR:

• [ ] Work In Progress
• [ ] bug
• [X ] enhancement
• [ ] documentation
• [ ] release
• [ ] high priority
• [ ] run_ci
• [ ] run_we2e_fundamental_tests
• [ ] run_we2e_comprehensive_tests
• [ ] Needs Cheyenne test
• [ ] Needs Jet test
• [ ] Needs Hera test
• [ ] Needs Orion test
• [ ] help wanted

CONTRIBUTORS (optional):

[chan-hoo]

@lwcugb, please add [aqm_dev] to your title as above when your PR is not for the develop branch.

[lwcugb]

@lwcugb, please add [aqm_dev] to your title as above when your PR is not for the develop branch.

Thanks and done!

[chan-hoo]

LGTM. approving