Don't allow interpolation from a non-ciso case to a ciso case

Due to ESCOMP#67, interpolation from a
case without carbon isotopes to a case with carbon isotopes yields
incorrect initialization values for the carbon isotopes. Now that we're
turning carbon isotopes on via some semi-out-of-the-box usermods (for
cmip6), it is becoming more important to check to make sure someone
doesn't shoot themselves in the foot this way.

This commit should be backed out once ESCOMP#67 is resolved

src/init_interp/initInterp.F90

@@ -49,6 +49,7 @@ module initInterpMod
   private :: interp_1d_int
   private :: interp_2d_double
   private :: limit_snlsno
+  private :: check_interp_non_ciso_to_ciso
 
   ! Private data
 
@@ -227,12 +228,14 @@ subroutine initInterp (filei, fileo, bounds, glc_behavior)
     end if
 
     ! --------------------------------------------
-    ! Open input and output initial conditions files (both just for reading now)
+    ! Open input and output initial conditions files
     ! --------------------------------------------
 
     call ncd_pio_openfile (ncidi, trim(filei) , 0)
     call ncd_pio_openfile (ncido, trim(fileo),  ncd_write)
 
+    call check_interp_non_ciso_to_ciso(ncidi)
+
     ! --------------------------------------------
     ! Determine dimensions and error checks on dimensions
     ! --------------------------------------------
@@ -1258,4 +1261,66 @@ subroutine limit_snlsno(ncido, bounds_o)
     deallocate(snlsno)
   end subroutine limit_snlsno
 
+  !-----------------------------------------------------------------------
+  subroutine check_interp_non_ciso_to_ciso(ncidi)
+    !
+    ! !DESCRIPTION:
+    ! BUG(wjs, 2018-10-25, ESCOMP/ctsm#67) There is a bug that causes incorrect values for
+    ! C isotopes if running init_interp from a case without C isotopes to a case with C
+    ! isotopes (https://github.com/ESCOMP/ctsm/issues/67). Here we check that the user
+    ! isn't trying to do an interpolation in that case. This check should be removed once
+    ! bug #67 is resolved.
+    !
+    ! !USES:
+    use clm_varctl, only : use_c13, use_c14, for_testing_allow_interp_non_ciso_to_ciso
+    !
+    ! !ARGUMENTS:
+    type(file_desc_t), intent(inout) :: ncidi
+    !
+    ! !LOCAL VARIABLES:
+    type(Var_desc_t)   :: vardesc         ! pio variable descriptor
+    integer            :: status          ! return code
+
+    character(len=*), parameter :: subname = 'check_interp_non_ciso_to_ciso'
+    !-----------------------------------------------------------------------
+
+    if (.not. for_testing_allow_interp_non_ciso_to_ciso) then
+       if (use_c13) then
+          call pio_seterrorhandling(ncidi, PIO_BCAST_ERROR)
+          ! arbitrarily check leafc_13 (we could pick any c13 restart field)
+          status = pio_inq_varid(ncidi, name='leafc_13', vardesc=vardesc)
+          call pio_seterrorhandling(ncidi, PIO_INTERNAL_ERROR)
+          if (status /= PIO_noerr) then
+             if (masterproc) then
+                write(iulog,*) 'Cannot interpolate from a run without c13 to a run with c13,'
+                write(iulog,*) 'due to <https://github.com/ESCOMP/ctsm/issues/67>.'
+                write(iulog,*) 'Either use an input initial conditions file with c13 information,'
+                write(iulog,*) 'or re-spinup from cold start.'
+             end if
+             call endrun(msg='Cannot interpolate from a run without c13 to a run with c13', &
+                  additional_msg=errMsg(sourcefile, __LINE__))
+          end if
+       end if
+
+       if (use_c14) then
+          call pio_seterrorhandling(ncidi, PIO_BCAST_ERROR)
+          ! arbitrarily check leafc_14 (we could pick any c14 restart field)
+          status = pio_inq_varid(ncidi, name='leafc_14', vardesc=vardesc)
+          call pio_seterrorhandling(ncidi, PIO_INTERNAL_ERROR)
+          if (status /= PIO_noerr) then
+             if (masterproc) then
+                write(iulog,*) 'Cannot interpolate from a run without c14 to a run with c14,'
+                write(iulog,*) 'due to <https://github.com/ESCOMP/ctsm/issues/67>.'
+                write(iulog,*) 'Either use an input initial conditions file with c14 information,'
+                write(iulog,*) 'or re-spinup from cold start.'
+             end if
+             call endrun(msg='Cannot interpolate from a run without c14 to a run with c14', &
+                  additional_msg=errMsg(sourcefile, __LINE__))
+          end if
+       end if
+    end if
+
+  end subroutine check_interp_non_ciso_to_ciso
+
+
 end module initInterpMod

src/main/clm_varctl.F90

@@ -189,6 +189,14 @@ module clm_varctl
   logical, public :: use_c13 = .false.                  ! true => use C-13 model
   logical, public :: use_c14 = .false.                  ! true => use C-14 model
 
+  ! BUG(wjs, 2018-10-25, ESCOMP/ctsm#67) There is a bug that causes incorrect values for C
+  ! isotopes if running init_interp from a case without C isotopes to a case with C
+  ! isotopes (https://github.com/ESCOMP/ctsm/issues/67). Normally, an error-check prevents
+  ! you from doing this interpolation (until we have fixed that bug). However, we
+  ! sometimes want to bypass this error-check in system tests. This namelist flag bypasses
+  ! this error-check.
+  logical, public :: for_testing_allow_interp_non_ciso_to_ciso = .false.
+
   !----------------------------------------------------------
   !  FATES switches
   !----------------------------------------------------------

src/main/controlMod.F90

@@ -214,7 +214,7 @@ subroutine control_init( )
 
     namelist /clm_inparm/ no_frozen_nitrif_denitrif
 
-    namelist /clm_inparm/ use_c13, use_c14
+    namelist /clm_inparm/ use_c13, use_c14, for_testing_allow_interp_non_ciso_to_ciso
 
 
     ! FATES Flags
@@ -628,6 +628,7 @@ subroutine control_spmd()
     ! isotopes
     call mpi_bcast (use_c13, 1, MPI_LOGICAL, 0, mpicom, ier)
     call mpi_bcast (use_c14, 1, MPI_LOGICAL, 0, mpicom, ier)
+    call mpi_bcast (for_testing_allow_interp_non_ciso_to_ciso, 1, MPI_LOGICAL, 0, mpicom, ier)
 
     call mpi_bcast (use_fates, 1, MPI_LOGICAL, 0, mpicom, ier)
 
@@ -864,6 +865,7 @@ subroutine control_print ()
        write(iulog, *) '  use_c14                                                : ', use_c14
        write(iulog, *) '  use_c14_bombspike                                      : ', use_c14_bombspike
        write(iulog, *) '  atm_c14_filename                                       : ', atm_c14_filename
+       write(iulog, *) '  for_testing_allow_interp_non_ciso_to_ciso              : ', for_testing_allow_interp_non_ciso_to_ciso
     end if
 
     if (fsnowoptics == ' ') then