--- MITgcm/pkg/ptracers/ptracers_integrate.F	2004/11/23 20:21:13	1.21
+++ MITgcm/pkg/ptracers/ptracers_integrate.F	2005/11/06 22:17:33	1.26
@@ -1,4 +1,4 @@
-C $Header: /home/ubuntu/mnt/e9_copy/MITgcm/pkg/ptracers/ptracers_integrate.F,v 1.21 2004/11/23 20:21:13 mlosch Exp $
+C $Header: /home/ubuntu/mnt/e9_copy/MITgcm/pkg/ptracers/ptracers_integrate.F,v 1.26 2005/11/06 22:17:33 jmc Exp $
 C $Name:  $
 
 #include "PTRACERS_OPTIONS.h"
@@ -15,7 +15,7 @@
      I                               myIter,myTime,myThid )
 
 C !DESCRIPTION:
-C     Calculates tendancy for passive tracers and integrates forward
+C     Calculates tendency for passive tracers and integrates forward
 C     in time.
 
 C !USES: ===============================================================
@@ -73,6 +73,7 @@
       INTEGER kUp,kDown,km1
       INTEGER GAD_TR
       LOGICAL calcAdvection
+      INTEGER iterNb
 CEOP
 
 C Loop over tracers
@@ -103,10 +104,11 @@
      I                   PTRACERS_diffK4(iTracer),
      I                   KappaRtr(1-Olx,1-Oly,iTracer),
      I                   pTracer(1-Olx,1-Oly,1,1,1,iTracer),
+     I                   pTracer(1-Olx,1-Oly,1,1,1,iTracer),
      I                   GAD_TR,
      I                   PTRACERS_advScheme(iTracer),
      I                   PTRACERS_advScheme(iTracer),
-     I                   calcAdvection, .FALSE.,
+     I                   calcAdvection, PTRACERS_ImplVertAdv(iTracer),
      U                   rFlx(1-Olx,1-Oly,1,iTracer),
      U                   gPtr(1-Olx,1-Oly,1,1,1,iTracer),
      I                   myTime, myIter, myThid )
@@ -120,14 +122,25 @@
      I                      myIter,myTime,myThid)
 
 C If using Adams-Bashforth II, then extrapolate tendancies
+C gPtr is now the tracer tendency for explicit advection/diffusion
       IF ( PTRACERS_advScheme(iTracer).EQ.ENUM_CENTERED_2ND
      & .OR.PTRACERS_advScheme(iTracer).EQ.ENUM_UPWIND_3RD
      & .OR.PTRACERS_advScheme(iTracer).EQ.ENUM_CENTERED_4TH ) THEN
+#ifdef ALLOW_MATRIX
+C  If matrix is being computed, block call to S/R ADAMS_BASHFORTH2 to 
+C  prevent gPtr from being replaced by the average of gPtr and gPtrNm1.    
+        IF (.NOT.useMATRIX) THEN
+#endif          
+        iterNb = myIter
+        IF (staggerTimeStep) iterNb = myIter - 1
         CALL ADAMS_BASHFORTH2(
      I                        bi,bj,K,
      U                        gPtr(1-Olx,1-Oly,1,1,1,iTracer),
      U                        gPtrNm1(1-Olx,1-Oly,1,1,1,iTracer),
-     I                        myIter,myThid )
+     I                        iterNb, myThid )
+#ifdef ALLOW_MATRIX
+        ENDIF
+#endif     
       ENDIF
 
 C External forcing term(s)
@@ -163,6 +176,15 @@
      I                        gPtr(1-Olx,1-Oly,1,1,1,iTracer),
      I                        myIter,myThid )
 
+#ifdef   ALLOW_OBCS
+C Apply open boundary conditions
+         IF (useOBCS) THEN
+          CALL OBCS_APPLY_PTRACER( 
+     I         bi, bj, k, iTracer, 
+     U         gPtr(1-Olx,1-Oly,k,bi,bj,iTracer),
+     I         myThid )
+         END IF
+#endif   /* ALLOW_OBCS */
 C end of tracer loop
       ENDDO