Updated some comments, added back protections on patch canopy areas e…

…xceeding 1 during the output boundary condition preparations.

biogeochem/EDCanopyStructureMod.F90

@@ -318,7 +318,7 @@ subroutine DemoteFromLayer(currentSite,currentPatch,i_lyr)
       ! !LOCAL VARIABLES:
       type(ed_cohort_type), pointer :: currentCohort,copyc
       integer  :: i_cwd                  ! Index for CWD pool
-      real(r8) :: cc_loss
+      real(r8) :: cc_loss                ! cohort crown area loss in demotion (m2)
       real(r8) :: lossarea
       real(r8) :: newarea
       real(r8) :: demote_area
@@ -638,7 +638,7 @@ subroutine PromoteIntoLayer(currentSite,currentPatch,i_lyr)
       integer  :: exceedance_counter
       real(r8) :: remainder_area
       real(r8) :: remainder_area_hold    
-      real(r8) :: cc_gain
+      real(r8) :: cc_gain                ! cohort crown area gain in promotion (m2)
       real(r8) :: arealayer_current      ! area (m2) of the current canopy layer
       real(r8) :: arealayer_below        ! area (m2) of the layer below the current layer
 
@@ -1628,9 +1628,11 @@ subroutine update_hlm_dynamics(nsites,sites,fcolumn,bc_out)
            ! currentPatch%total_canopy_area/currentPatch%area is fraction of this patch cover by plants 
            ! currentPatch%area/AREA is the fraction of the soil covered by this patch. 
 
-           bc_out(s)%canopy_fraction_pa(ifp) = currentPatch%total_canopy_area/AREA
+           bc_out(s)%canopy_fraction_pa(ifp) = &
+                min(1.0_r8,currentPatch%total_canopy_area/currentPatch%area)*(currentPatch%area/AREA)
 
-           bare_frac_area = (1.0_r8-currentPatch%total_canopy_area/currentPatch%area)*(currentPatch%area/AREA)
+           bare_frac_area = (1.0_r8 - min(1.0_r8,currentPatch%total_canopy_area/currentPatch%area)) * &
+                (currentPatch%area/AREA)
 
            total_patch_area = total_patch_area + bc_out(s)%canopy_fraction_pa(ifp) + bare_frac_area
 
@@ -1674,8 +1676,10 @@ subroutine update_hlm_dynamics(nsites,sites,fcolumn,bc_out)
               call endrun(msg=errMsg(sourcefile, __LINE__))
            end if
 
-           write(fates_log(),*) 'imprecise patch areas in update_hlm_dynamics',total_patch_area
-
+           if(DEBUG) then
+              write(fates_log(),*) 'imprecise patch areas in update_hlm_dynamics',total_patch_area
+           end if
+
            currentPatch => sites(s)%oldest_patch
            ifp = 0
            do while(associated(currentPatch))

biogeochem/EDPatchDynamicsMod.F90

@@ -36,6 +36,7 @@ module EDPatchDynamicsMod
   use FatesConstantsMod    , only : ha_per_m2
   use FatesConstantsMod    , only : days_per_sec
   use FatesConstantsMod    , only : years_per_day
+  use FatesConstantsMod    , only : nearzero
 
 
   ! CIME globals
@@ -730,9 +731,14 @@ subroutine check_patch_area( currentSite )
 
        if ( abs(areatot-area) > area_error_fail ) then
           write(fates_log(),*) 'Patch areas do not sum to 10000 within tolerance'
-          write(fates_log(),*) 'Total area: ': areatot,'absolute error: ',areatot-area
+          write(fates_log(),*) 'Total area: ',areatot,'absolute error: ',areatot-area
           call endrun(msg=errMsg(sourcefile, __LINE__))
        end if
+
+       if(debug) then
+          write(fates_log(),*) 'Total patch area precision being fixed, adjusting'
+          write(fates_log(),*) 'largest patch. This may have slight impacts on carbon balance.'
+       end if
 
        largestPatch%area = largestPatch%area + (area-areatot)