Introduce GEOM_FILE runtime parameter to set ocean_geometry file name.

This is to enable the prefixing of the ocean geometry file with the case
(experiment) name, and thus enable adherence to CESM output file naming
convention and allow short term archiving of ocean_geometry file.

src/core/MOM.F90

@@ -2117,6 +2117,7 @@ subroutine initialize_MOM(Time, Time_init, param_file, dirs, CS, &
   type(ocean_internal_state)      :: MOM_internal_state
   type(MOM_domain_type), pointer  :: MOM_dom_unmasked => null() ! Unmasked MOM domain instance
                                                                 ! (To be used for writing out ocean geometry)
+  character(len=240) :: geom_file ! Name of the ocean geometry file
 
   CS%Time => Time
 
@@ -2464,6 +2465,9 @@ subroutine initialize_MOM(Time, Time_init, param_file, dirs, CS, &
                  "vertical grid files. Other values are invalid.", default=1)
   if (write_geom<0 .or. write_geom>2) call MOM_error(FATAL,"MOM: "//&
          "WRITE_GEOM must be equal to 0, 1 or 2.")
+  call get_param(param_file, "MOM", "GEOM_FILE", geom_file, &
+                 "The file into which to write the ocean geometry.", &
+                 default="ocean_geometry")
   call get_param(param_file, "MOM", "USE_DBCLIENT", CS%use_dbclient, &
                  "If true, initialize a client to a remote database that can "//&
                  "be used for online analysis and machine-learning inference.",&
@@ -2853,11 +2857,11 @@ subroutine initialize_MOM(Time, Time_init, param_file, dirs, CS, &
       call create_dyn_horgrid(dG_unmasked_in, HI_in_unmasked, bathymetry_at_vel=bathy_at_vel)
       call clone_MOM_domain(MOM_dom_unmasked, dG_unmasked_in%Domain)
       call MOM_initialize_fixed(dG_unmasked_in, US, OBC_in, param_file, .false., dirs%output_directory)
-      call write_ocean_geometry_file(dG_unmasked_in, param_file, dirs%output_directory, US=US)
+      call write_ocean_geometry_file(dG_unmasked_in, param_file, dirs%output_directory, US=US, geom_file=geom_file)
       call deallocate_MOM_domain(MOM_dom_unmasked)
       call destroy_dyn_horgrid(dG_unmasked_in)
     else
-      call write_ocean_geometry_file(dG_in, param_file, dirs%output_directory, US=US)
+      call write_ocean_geometry_file(dG_in, param_file, dirs%output_directory, US=US, geom_file=geom_file)
     endif
   endif
   call destroy_dyn_horgrid(dG_in)