--- MITgcm/pkg/diagnostics/diagnostics_write.F	2004/12/13 21:55:48	1.8
+++ MITgcm/pkg/diagnostics/diagnostics_write.F	2005/02/06 23:19:02	1.9
@@ -1,9 +1,9 @@
-C $Header: /home/ubuntu/mnt/e9_copy/MITgcm/pkg/diagnostics/diagnostics_write.F,v 1.8 2004/12/13 21:55:48 jmc Exp $
+C $Header: /home/ubuntu/mnt/e9_copy/MITgcm/pkg/diagnostics/diagnostics_write.F,v 1.9 2005/02/06 23:19:02 jmc Exp $
 C $Name:  $
 
 #include "DIAG_OPTIONS.h"
 
-      SUBROUTINE DIAGNOSTICS_WRITE ( myIter, myThid ) 
+      SUBROUTINE DIAGNOSTICS_WRITE ( myTime, myIter, myThid ) 
 C***********************************************************************
 C  Purpose
 C  -------
@@ -11,8 +11,9 @@
 C
 C  Arguments  Description
 C  ----------------------
-C     myIter ..... Current Iteration Number
-C     myThid ..... my thread Id number
+C     myTime :: Current time of simulation ( s )
+C     myIter :: Current Iteration Number
+C     myThid :: my thread Id number
 C***********************************************************************
        IMPLICIT NONE
 #include "SIZE.h"
@@ -21,28 +22,49 @@
 #include "EEPARAMS.h"
 #include "PARAMS.h"
 
+      _RL     myTime
       INTEGER myIter, myThid
 
 c Local variables
 c ===============
       INTEGER   n
+      INTEGER   myItM1, wrIter
+      LOGICAL   dump2fileNow
 
-      IF ( myIter.ne.nIter0 ) THEN
+      IF ( myIter.NE.nIter0 ) THEN
+        myItM1 = myIter - 1
 
 C***********************************************************************
 C***   Check to see IF its time for Diagnostic Output                ***
 C***********************************************************************
 
         DO n = 1,nlists
-          IF ( MOD(myIter,freq(n)).EQ.0 ) THEN
-            CALL DIAGNOSTICS_OUT(n,myIter,myThid)
+          IF ( freq(n).LT.0 ) THEN
+            dump2fileNow = MOD(myItM1,-freq(n)) .EQ. INT(-freq(n)/2)
+C--     write snap-shot with suffix = myIter to be consistent with 
+C       time-average diagnostics (e.g., freq=-1 & freq=1):
+c           wrIter = myIter
+C--     write snap-shot with suffix = myIter-1 to be consistent with
+C       state-variable time-step:
+            wrIter = myItM1
+          ELSE
+            dump2fileNow = MOD(myIter,freq(n)) .EQ. 0
+            wrIter = myIter
+          ENDIF
+          IF ( dump2fileNow ) THEN
+            CALL DIAGNOSTICS_OUT(n,wrIter,myThid)
           ENDIF
         ENDDO
 
 C-      wait for everyone before setting arrays to zero: 
         _BARRIER
         DO n = 1,nlists
-          IF ( MOD(myIter,freq(n)).EQ.0 ) CALL CLRINDX(n,myThid)
+          IF ( freq(n).LT.0 ) THEN
+            dump2fileNow = MOD(myItM1,-freq(n)) .EQ. INT(-freq(n)/2)
+          ELSE
+            dump2fileNow = MOD(myIter,freq(n)) .EQ. 0
+          ENDIF
+          IF ( dump2fileNow ) CALL CLRINDX(n,myThid)
         ENDDO
 
 C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|