Make: *** [combine.exe] Error 2 undefined reference to `nf_get_vara_text_

CMAQ Post-processing
2

This may or may not be the cause of the problem, but it seems you have different options for second_underscore in Makeinclude.Linux3.txt and Makefile_combine.txt

Makeinclude.Linux3.txt:

FOPTFLAGS = -O2 -V -Mnosecond_underscore

Makefile_combine.txt:

FSTD = -Mextend -O2 -fast -V -Msecond_underscore

Try changing the setting in Makefile_combine.txt to -Mnosecond_underscore to match what you did when you built I/O API.

I think this may be the exact same issue you ran into when compiling airs2m3, and the solution may also be the same.