Changeset 6343

Timestamp:

2016-02-23T10:36:53+01:00 (8 years ago)

Author:

frrh

Message:

Commit working version demonstrating bit comparable results over different PE
decompositions.

Here we use the function "glob_sum" to ensure bit reproducible
global summation and we rejig the code slightly to avoid
duplicating the summation of the mask varaiable.

This simplifies the code slightly too because we no longer have to
do local sums followed by a global sum, we just have a single call
top glob_sum in each case.

Location:

branches/UKMO/dev_r5518_fix_global_ice/NEMOGCM/NEMO/OPA_SRC/SBC

Files:

• sbccpl.F90 (modified) (3 diffs)
• sbcisf.F90 (modified) (7 diffs)

branches/UKMO/dev_r5518_fix_global_ice/NEMOGCM/NEMO/OPA_SRC/SBC/sbccpl.F90

@@ -49 +49 @@
    USE limthd_dh       ! for CALL lim_thd_snwblow
 #endif
+   USE lib_fortran, ONLY: glob_sum
 
    IMPLICIT NONE
@@ -1271 +1272 @@
       zepsilon = rn_iceshelf_fluxes_tolerance
 
+
+      ! See if we need zmask_sum...
+      IF ( srcv(jpr_grnm)%laction .OR. srcv(jpr_antm)%laction ) THEN
+         zmask_sum = glob_sum( tmask(:,:,1) )
+      ENDIF
+
       IF( srcv(jpr_grnm)%laction ) THEN
          greenland_icesheet_mass_array(:,:) = frcv(jpr_grnm)%z3(:,:,1)
          ! take average over ocean points of input array to avoid cumulative error over time
-         zgreenland_icesheet_mass_in = SUM( greenland_icesheet_mass_array(:,:) * tmask(:,:,1) )
-         IF(lk_mpp) CALL mpp_sum( zgreenland_icesheet_mass_in )
-         zmask_sum = SUM( tmask(:,:,1) )
-         IF(lk_mpp) CALL mpp_sum( zmask_sum ) 
+
+         ! The following must be bit reproducible over different PE decompositions
+         zgreenland_icesheet_mass_in = glob_sum( greenland_icesheet_mass_array(:,:) * tmask(:,:,1) )
+
          zgreenland_icesheet_mass_in = zgreenland_icesheet_mass_in / zmask_sum
          greenland_icesheet_timelapsed = greenland_icesheet_timelapsed + rdt         
@@ -1302 +1309 @@
          antarctica_icesheet_mass_array(:,:) = frcv(jpr_antm)%z3(:,:,1)
          ! take average over ocean points of input array to avoid cumulative error from rounding errors over time
-         zantarctica_icesheet_mass_in = SUM( antarctica_icesheet_mass_array(:,:) * tmask(:,:,1) )
-         IF(lk_mpp) CALL mpp_sum( zantarctica_icesheet_mass_in )
-         zmask_sum = SUM( tmask(:,:,1) )
-         IF(lk_mpp) CALL mpp_sum( zmask_sum ) 
+         ! The following must be bit reproducible over different PE decompositions
+         zantarctica_icesheet_mass_in = glob_sum( antarctica_icesheet_mass_array(:,:) * tmask(:,:,1) )
+
          zantarctica_icesheet_mass_in = zantarctica_icesheet_mass_in / zmask_sum
          antarctica_icesheet_timelapsed = antarctica_icesheet_timelapsed + rdt         

branches/UKMO/dev_r5518_fix_global_ice/NEMOGCM/NEMO/OPA_SRC/SBC/sbcisf.F90

@@ -26 +26 @@
    USE zdfbfr
    USE fldread         ! read input field at current time step
+   USE lib_fortran, ONLY: glob_sum
 
    IMPLICIT NONE
@@ -263 +264 @@
               ! and southern hemispheres equals rate of increase of mass of greenland and antarctic ice sheets
               ! to preserve total freshwater conservation in coupled models without an active ice sheet model.
-
-               zgreenland_fwfisf_sum = SUM( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * greenland_icesheet_mask(:,:) )
-               IF( lk_mpp ) CALL mpp_sum( zgreenland_fwfisf_sum )
+ 
+              ! All related global sums must be done bit reproducibly
+               zgreenland_fwfisf_sum = glob_sum( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * greenland_icesheet_mask(:,:) )
+
                ! use ABS function because we need to preserve the sign of fwfisf
                WHERE( greenland_icesheet_mask(:,:) == 1.0 )                                                                  &
@@ -273 +275 @@
                ! check
                IF(lwp) WRITE(numout, *) 'Greenland iceshelf melting climatology (kg/s) : ',zgreenland_fwfisf_sum
-               zgreenland_fwfisf_sum = SUM( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * greenland_icesheet_mask(:,:) )
-               IF( lk_mpp ) CALL mpp_sum( zgreenland_fwfisf_sum )
+
+               zgreenland_fwfisf_sum = glob_sum( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * greenland_icesheet_mask(:,:) )
+
                IF(lwp) WRITE(numout, *) 'Greenland iceshelf melting adjusted value (kg/s) : ',zgreenland_fwfisf_sum
 
-               zantarctica_fwfisf_sum = SUM( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * antarctica_icesheet_mask(:,:) )
-               IF( lk_mpp ) CALL mpp_sum( zantarctica_fwfisf_sum )
+               zantarctica_fwfisf_sum = glob_sum( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * antarctica_icesheet_mask(:,:) )
+
                ! use ABS function because we need to preserve the sign of fwfisf
                WHERE( antarctica_icesheet_mask(:,:) == 1.0 ) &
@@ -286 +289 @@
                ! check
                IF(lwp) WRITE(numout, *) 'Antarctica iceshelf melting climatology (kg/s) : ',zantarctica_fwfisf_sum
-               zantarctica_fwfisf_sum = SUM( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * antarctica_icesheet_mask(:,:) )
-               IF( lk_mpp ) CALL mpp_sum( zantarctica_fwfisf_sum )
+
+               zantarctica_fwfisf_sum = glob_sum( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * antarctica_icesheet_mask(:,:) )
+
                IF(lwp) WRITE(numout, *) 'Antarctica iceshelf melting adjusted value (kg/s) : ',zantarctica_fwfisf_sum
 
@@ -310 +314 @@
               ! to preserve total freshwater conservation in coupled models without an active ice sheet model.
 
-               zgreenland_fwfisf_sum = SUM( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * greenland_icesheet_mask(:,:) )
-               IF( lk_mpp ) CALL mpp_sum( zgreenland_fwfisf_sum )
+              ! All related global sums must be done bit reproducibly
+               zgreenland_fwfisf_sum = glob_sum( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * greenland_icesheet_mask(:,:) )
+
                ! use ABS function because we need to preserve the sign of fwfisf
                WHERE( greenland_icesheet_mask(:,:) == 1.0 )                                                                  &
@@ -319 +324 @@
                ! check
                IF(lwp) WRITE(numout, *) 'Greenland iceshelf melting climatology (kg/s) : ',zgreenland_fwfisf_sum
-               zgreenland_fwfisf_sum = SUM( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * greenland_icesheet_mask(:,:) )
-               IF( lk_mpp ) CALL mpp_sum( zgreenland_fwfisf_sum )
+
+               zgreenland_fwfisf_sum = glob_sum( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * greenland_icesheet_mask(:,:) )
+
                IF(lwp) WRITE(numout, *) 'Greenland iceshelf melting adjusted value (kg/s) : ',zgreenland_fwfisf_sum
 
-               zantarctica_fwfisf_sum = SUM( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * antarctica_icesheet_mask(:,:) )
-               IF( lk_mpp ) CALL mpp_sum( zantarctica_fwfisf_sum )
+               zantarctica_fwfisf_sum = glob_sum( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * antarctica_icesheet_mask(:,:) )
+
                ! use ABS function because we need to preserve the sign of fwfisf
                WHERE( antarctica_icesheet_mask(:,:) == 1.0 ) &
@@ -332 +338 @@
                ! check
                IF(lwp) WRITE(numout, *) 'Antarctica iceshelf melting climatology (kg/s) : ',zantarctica_fwfisf_sum
-               zantarctica_fwfisf_sum = SUM( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * antarctica_icesheet_mask(:,:) )
-               IF( lk_mpp ) CALL mpp_sum( zantarctica_fwfisf_sum )
+
+               zantarctica_fwfisf_sum = glob_sum( fwfisf(:,:) * e1t(:,:) * e2t(:,:) * antarctica_icesheet_mask(:,:) )
+
                IF(lwp) WRITE(numout, *) 'Antarctica iceshelf melting adjusted value (kg/s) : ',zantarctica_fwfisf_sum