major changes to relaxation coefficient setting:

- rename parameters cheapaml_taurelax & cheapaml_taurelaxocean (in days)
  to cheap_tauRelax & cheap_tauRelaxOce (now in seconds);
- if using cheapMaskFile, set relaxation coeff to: cheapMask/tauRelax
  (instead of 1/cheapMask over ocean and 1/tauRelax over land);
- with cheapMaskFile unset: set relaxation coeff according to land/ocean mask
  (unchanged) but skip increase near domain edges for periodic domain (in X
  or Y dir) when cheapamlX/Yperiodic=T ; also fix linear increase (over
  Cheapaml_mask_width grid points) of coeff towards domain edges (previously
  was increasing away from edges). Update output of experiment "cheapAML_box".
Leave old code under #ifdef CHEAPAML_OLD_MASK_SETTING / #endif

pkg/cheapaml/cheapaml_init_fixed.F

@@ -1,7 +1,8 @@
-C $Header: /u/gcmpack/MITgcm/pkg/cheapaml/cheapaml_init_fixed.F,v 1.7 2017/10/12 15:40:07 jmc Exp $
+C $Header: /u/gcmpack/MITgcm/pkg/cheapaml/cheapaml_init_fixed.F,v 1.8 2017/10/13 17:48:03 jmc Exp $
 C $Name:  $
 
 #include "CHEAPAML_OPTIONS.h"
+#undef CHEAPAML_OLD_MASK_SETTING
 
 CBOP
 C     !ROUTINE: CHEAPAML_INIT_FIXED
@@ -42,12 +43,15 @@ SUBROUTINE CHEAPAML_INIT_FIXED( myThid )
       INTEGER i, j
       INTEGER iG,jG
       INTEGER xmw
-      _RL xmf
-      _RL recipMW
+      _RL xmf, tmpVar
       _RL relaxMask(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
       _RL xgs      (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
       INTEGER iL, ioUnit
       CHARACTER*(MAX_LEN_MBUF) msgBuf
+#ifdef CHEAPAML_OLD_MASK_SETTING
+      _RL recipMW
+      _RL cheapaml_taurelax, cheapaml_taurelaxocean
+#endif /* CHEAPAML_OLD_MASK_SETTING */
 CEOP
 
 C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
@@ -66,6 +70,10 @@ SUBROUTINE CHEAPAML_INIT_FIXED( myThid )
        ENDDO
       ENDDO
 
+#ifdef CHEAPAML_OLD_MASK_SETTING
+      cheapaml_taurelax      =  cheap_tauRelax   /86400. _d 0
+      cheapaml_taurelaxocean =  cheap_tauRelaxOce/86400. _d 0
+
 c--   Setup CheapAML mask (for relaxation):
 C Do  mask
       IF ( cheapMaskFile .NE. ' ') THEN
@@ -148,9 +156,104 @@ SUBROUTINE CHEAPAML_INIT_FIXED( myThid )
          ENDDO
         ENDDO
        ENDDO
+c      _EXCH_XY_RL( xgs, myThid )
+c      _EXCH_XY_RL( xrelf, myThid )
+
+#else /* CHEAPAML_OLD_MASK_SETTING */
+
+C--   Setup CheapAML mask (for relaxation):
+      IF ( cheapMaskFile .NE. ' ' ) THEN
+C-    read mask from file
+        iL = ILNBLNK(cheapMaskFile)
+        WRITE(msgBuf,'(4A)') 'CHEAPAML_INIT_VARIA: ',
+     &      'Relaxation Mask read from ->', cheapMaskFile(1:iL), '<-'
+        CALL PRINT_MESSAGE( msgBuf, ioUnit, SQUEEZE_RIGHT, myThid )
+        CALL READ_FLD_XY_RL( cheapMaskFile,' ',relaxMask,0,myThid )
+      ELSE
+        WRITE(msgBuf,'(4A)') 'CHEAPAML_INIT_VARIA: ',
+     &     'Generate Cheapaml mask'
+        CALL PRINT_MESSAGE( msgBuf, ioUnit, SQUEEZE_RIGHT, myThid )
+        DO bj = myByLo(myThid), myByHi(myThid)
+         DO bi = myBxLo(myThid), myBxHi(myThid)
+C-    set mask according to boundaries
+          IF ( Cheapaml_mask_width.LE.0 .OR.
+     &         ( cheapamlXperiodic .AND. cheapamlYperiodic ) ) THEN
+            DO j=1,sNy
+             DO i=1,sNx
+               relaxMask(i,j,bi,bj) = 0.
+             ENDDO
+            ENDDO
+          ELSE
+            xmw = Cheapaml_mask_width
+            tmpVar = xmw
+            tmpVar = oneRL / tmpVar
+            DO j=1,sNy
+             DO i=1,sNx
+              xmf = 0. _d 0
+              iG = myXGlobalLo-1+(bi-1)*sNx+i
+              jG = myYGlobalLo-1+(bj-1)*sNy+j
+              IF ( .NOT.cheapamlXperiodic ) THEN
+                IF (iG.LE.xmw)      xmf = oneRL - (iG-1 )*tmpVar
+                IF (iG.GE.Nx-xmw+1) xmf = oneRL - (Nx-iG)*tmpVar
+              ENDIF
+              IF ( .NOT.cheapamlYperiodic ) THEN
+                IF (jG.LE.xmw)
+     &                    xmf = MAX( xmf, oneRL - (jG-1 )*tmpVar )
+                IF (jG.GE.Ny-xmw+1)
+     &                    xmf = MAX( xmf, oneRL - (Ny-jG)*tmpVar )
+              ENDIF
+              relaxMask(i,j,bi,bj) = xmf
+             ENDDO
+            ENDDO
+          ENDIF
+C-    set mask to one over land:
+          DO j=1,sNy
+            DO i=1,sNx
+              relaxMask(i,j,bi,bj) = MAX( relaxMask(i,j,bi,bj),
+     &                               (oneRL - maskC(i,j,1,bi,bj)) )
+            ENDDO
+          ENDDO
+         ENDDO
+        ENDDO
+      ENDIF
+      _EXCH_XY_RL( relaxMask, myThid )
 
-       _EXCH_XY_RL( xgs, myThid )
-       _EXCH_XY_RL( xrelf, myThid )
+C-    Set relaxation coeff "xgs"
+      DO bj = myByLo(myThid), myByHi(myThid)
+       DO bi = myBxLo(myThid), myBxHi(myThid)
+         IF ( cheap_tauRelax .LE. zeroRL ) THEN
+           DO j=1-OLy,sNy+OLy
+            DO i=1-OLx,sNx+OLx
+              xgs(i,j,bi,bj) = 0. _d 0
+            ENDDO
+           ENDDO
+         ELSE
+           tmpVar =  oneRL/cheap_tauRelax
+           DO j=1-OLy,sNy+OLy
+            DO i=1-OLx,sNx+OLx
+              xgs(i,j,bi,bj) = relaxMask(i,j,bi,bj)*tmpVar
+            ENDDO
+           ENDDO
+         ENDIF
+         IF ( cheap_tauRelaxOce .GT. zeroRL
+     &        .AND. cheapMaskFile .EQ. ' ' ) THEN
+           tmpVar =  oneRL/cheap_tauRelaxOce
+           DO j=1-OLy,sNy+OLy
+            DO i=1-OLx,sNx+OLx
+              xgs(i,j,bi,bj) = MAX( xgs(i,j,bi,bj), tmpVar )
+            ENDDO
+           ENDDO
+         ENDIF
+C-    Calculate implicit relaxation factor "xrelf"
+         DO j=1-OLy,sNy+OLy
+          DO i=1-OLx,sNx+OLx
+            tmpVar = xgs(i,j,bi,bj)*deltaT
+            xrelf(i,j,bi,bj)= tmpVar/( oneRL + tmpVar )
+          ENDDO
+         ENDDO
+       ENDDO
+      ENDDO
+#endif /* CHEAPAML_OLD_MASK_SETTING */
 
       IF ( debugLevel.GE.debLevB .AND. nIter0.EQ.0 ) THEN
         CALL WRITE_FLD_XY_RL('CheapMask',  ' ', relaxMask, 0, myThid )