Merge branch 'dustcontrolincmeps' of github.com:ekluzek/CTSM into dus…

…tcontrolincmeps

Also add a deisgn note the dust emission factory.
 Conflicts:
	bld/unit_testers/build-namelist_test.pl

src/biogeochem/DustEmisFactory.F90

@@ -25,6 +25,16 @@ function create_dust_emissions(bounds, NLFilename) result(dust_emis)
         !---------------------------------------------------------------------------
         ! Create a dust_emission base class objecct
         ! The method implemented depends on namelist input
+        !
+        ! DESIGN NOTES:   Erik Kluzek 07/15/2024
+        !     This implementation is different from for example the Fire Factory functions
+        !     that use a direct namelist item with case statements to determine the method.
+        !     Here we use logical functions from the shr_dust_emis_mod code. Because shr_dust_emis_mod
+        !     is used by both CTSM and CAM I wanted it to be robust with neither CAM nor CTSM
+        !     being able to change internal settings so a functional programming design was used
+        !     (with function calls that can't change anything inside shr_dust_emis_mod). This is also
+        !     why I added a unit-tester for the shr_dust_emis_mod code, so that both CTSM and CAM
+        !     can rely on it's behavior.
         !---------------------------------------------------------------------------
         use DustEmisBase      , only : dust_emis_base_type
         use DustEmisZender2003, only : dust_emis_zender2003_type