Merge branch 'wlin/lnd/nml_nbalance_err_tol' (PR #6651)

This enables namelist control for the balance_check_tolerance.
The hardwired default of balance_check_tolerance is increased from
1e-8 to 1e-7 for C, N and P based on testing results from investigating a runtime
failure due to grid and column nbalance errors exceeding specified
threshold.

[BFB] for tests never having nbalance issue
[NML] no NML diff for tests as default is not set via nml.

components/elm/bld/namelist_files/namelist_definition.xml

@@ -139,6 +139,12 @@ If TRUE consider priority of plant to get a fraction of
 symbiotic N fixation and P phosphatase
 </entry>
 
+<entry id="bgc_balance_check_tolerance" type="real" category="elm_physics"
+       group="elm_inparm" valid_values="" >
+BGC balance check tolerance
+Default 1.0e-7 hardwired
+</entry>
+
 <entry id="startdate_add_temperature" type="char*8" category="elm_physics"
        group="elm_inparm" valid_values="" >
 Set date for beginning of adding temperature to atmospheric forcing

components/elm/src/biogeochem/EcosystemBalanceCheckMod.F90

@@ -48,7 +48,10 @@ module EcosystemBalanceCheckMod
   implicit none
   save
   private
-  real(r8), parameter :: balance_check_tolerance = 1e-8_r8
+
+  ! This corersponds to namelist variable bgc_balance_check_tolerance
+  real(r8), public  :: balance_check_tolerance = 1e-7_r8
+
   !
   ! !PUBLIC MEMBER FUNCTIONS:
   public :: BeginColCBalance
@@ -278,7 +281,7 @@ subroutine ColCBalanceCheck(bounds, &
          end if
 
          ! check for significant errors
-         if (abs(col_errcb(c)) > 1e-8_r8) then
+         if (abs(col_errcb(c)) > balance_check_tolerance) then
             err_found = .true.
             err_index = c
          end if
@@ -498,7 +501,7 @@ subroutine ColNBalanceCheck(bounds, &
             ! here is '-' adjustment. It says that the adding to PF decomp n pools was less.
          end if
 
-         if (abs(col_errnb(c)) > 1e-8_r8) then
+         if (abs(col_errnb(c)) > balance_check_tolerance) then
             err_found = .true.
             err_index = c
          end if
@@ -731,7 +734,7 @@ subroutine ColPBalanceCheck(bounds, &
          col_errpb(c) = (col_pinputs(c) - col_poutputs(c))*dt - &
               (col_endpb(c) - col_begpb(c))
 
-         if (abs(col_errpb(c)) > 1e-8_r8) then
+         if (abs(col_errpb(c)) > balance_check_tolerance) then
             err_found = .true.
             err_index = c
          end if

components/elm/src/main/controlMod.F90

@@ -55,6 +55,7 @@ module controlMod
   use elm_varctl              , only: const_climate_hist
   use elm_varctl              , only: use_top_solar_rad
   use elm_varctl              , only: snow_shape, snicar_atm_type, use_dust_snow_internal_mixing
+  use EcosystemBalanceCheckMod, only: bgc_balance_check_tolerance => balance_check_tolerance
 
   !
   ! !PUBLIC TYPES:
@@ -181,6 +182,10 @@ subroutine control_init( )
     namelist /elm_inparm/ &
          NFIX_PTASE_plant
 
+    ! BGC balance check
+    namelist /elm_inparm/ &
+         bgc_balance_check_tolerance
+
     ! For experimental manipulations
     namelist /elm_inparm/ &
          startdate_add_temperature
@@ -325,7 +330,7 @@ subroutine control_init( )
 
     namelist /elm_mosart/ &
          lnd_rof_coupling_nstep
-		 
+
     namelist /elm_inparm/ &
          snow_shape, snicar_atm_type, use_dust_snow_internal_mixing 
 
@@ -796,6 +801,7 @@ subroutine control_spmd()
     call mpi_bcast (forest_fert_exp, 1, MPI_LOGICAL, 0, mpicom, ier)
     call mpi_bcast (ECA_Pconst_RGspin, 1, MPI_LOGICAL, 0, mpicom, ier)
     call mpi_bcast (NFIX_PTASE_plant, 1, MPI_LOGICAL, 0, mpicom, ier)
+    call mpi_bcast (bgc_balance_check_tolerance, 1, MPI_REAL8, 0, mpicom, ier)
     call mpi_bcast (use_pheno_flux_limiter, 1, MPI_LOGICAL, 0, mpicom, ier)
     call mpi_bcast (startdate_add_temperature, 1, MPI_CHARACTER, 0, mpicom, ier)
     call mpi_bcast (startdate_add_co2, 1, MPI_CHARACTER, 0, mpicom, ier)