Sfcsub needs re-factoring #344
Description
Description
The sfcsub routine is old, overly long, includes out-dated legacy code, and is difficult to understand.
Solution
The main improvements needed are:
- Remove un-used code
- Refactor into smaller subroutines
- Modernize to Fortran 90+ free-form to improve readability
- Create data structures for related field groups (e.g., a surface_field type)
- Consolidate QC logic into fewer re-usable routines
- Remove GRIB1 dependencies or clearly separate format handling
- Add comprehensive inline documentation explaining the physics