model/src/ini_cg2d.F

C $Header: /u/gcmpack/MITgcm/model/src/ini_cg2d.F,v 1.43 2005/07/20 22:33:02 jmc Exp $
C $Name:  $

#include "PACKAGES_CONFIG.h"
#include "CPP_OPTIONS.h"

CBOP
C     !ROUTINE: INI_CG2D
C     !INTERFACE:
      SUBROUTINE INI_CG2D( myThid )

C     !DESCRIPTION: \bv
C     *==========================================================*
C     | SUBROUTINE INI_CG2D                                       
C     | o Initialise 2d conjugate gradient solver operators.      
C     *==========================================================*
C     | These arrays are purely a function of the basin geom.     
C     | We set then here once and them use then repeatedly.       
C     *==========================================================*
C     \ev

C     !USES:
      IMPLICIT NONE
C     === Global variables ===
#include "SIZE.h"
#include "EEPARAMS.h"
#include "PARAMS.h"
#include "GRID.h"
#include "SURFACE.h"
#include "CG2D.h"
#ifdef ALLOW_OBCS
#include "OBCS.h"
#endif

C     !INPUT/OUTPUT PARAMETERS:
C     === Routine arguments ===
C     myThid - Thread no. that called this routine.
      INTEGER myThid

C     !LOCAL VARIABLES:
C     === Local variables ===
C     xG, yG - Global coordinate location.
C     zG
C     iG, jG - Global coordinate index
C     bi,bj  - Loop counters
C     faceArea - Temporary used to hold cell face areas.
C     I,J,K
C     myNorm - Work variable used in calculating normalisation factor
C     sumArea - Work variable used to compute the total Domain Area 
      CHARACTER*(MAX_LEN_MBUF) msgBuf
      INTEGER bi, bj
      INTEGER I,  J, K
      _RL     faceArea
      _RS     myNorm
      _RL     aC, aCw, aCs
CEOP

C--   Initialize arrays in common blocs (CG2D.h) ; not really necessary 
C     but safer when EXCH do not fill all the overlap regions.
      DO bj=myByLo(myThid),myByHi(myThid)
       DO bi=myBxLo(myThid),myBxHi(myThid)
        DO J=1-OLy,sNy+OLy
         DO I=1-OLx,sNx+OLx
          aW2d(I,J,bi,bj) = 0. _d 0
          aS2d(I,J,bi,bj) = 0. _d 0
          pW(I,J,bi,bj) = 0. _d 0
          pS(I,J,bi,bj) = 0. _d 0
          pC(I,J,bi,bj) = 0. _d 0
          cg2d_q(I,J,bi,bj) = 0. _d 0
         ENDDO
        ENDDO
        DO J=1-1,sNy+1
         DO I=1-1,sNx+1
          cg2d_r(I,J,bi,bj) = 0. _d 0
          cg2d_s(I,J,bi,bj) = 0. _d 0
         ENDDO
        ENDDO
       ENDDO
      ENDDO

C--   Initialise laplace operator
C     aW2d: integral in Z Ax/dX
C     aS2d: integral in Z Ay/dY
      myNorm = 0. _d 0
      DO bj=myByLo(myThid),myByHi(myThid)
       DO bi=myBxLo(myThid),myBxHi(myThid)
        DO J=1,sNy
         DO I=1,sNx
          aW2d(I,J,bi,bj) = 0. _d 0
          aS2d(I,J,bi,bj) = 0. _d 0
         ENDDO
        ENDDO
        DO K=1,Nr
         DO J=1,sNy
          DO I=1,sNx
           faceArea = _dyG(I,J,bi,bj)*drF(K)
     &               *_hFacW(I,J,K,bi,bj)
           aW2d(I,J,bi,bj) = aW2d(I,J,bi,bj) + 
     &      implicSurfPress*implicDiv2DFlow
     &           *faceArea*recip_dxC(I,J,bi,bj)
           faceArea = _dxG(I,J,bi,bj)*drF(K)
     &               *_hFacS(I,J,K,bi,bj)
           aS2d(I,J,bi,bj) = aS2d(I,J,bi,bj) + 
     &      implicSurfPress*implicDiv2DFlow
     &           *faceArea*recip_dyC(I,J,bi,bj)
          ENDDO
         ENDDO
        ENDDO
#ifdef ALLOW_OBCS
        IF (useOBCS) THEN
         DO I=1,sNx
          IF (OB_Jn(I,bi,bj).NE.0) aS2d(I,OB_Jn(I,bi,bj),bi,bj)=0.
          IF (OB_Jn(I,bi,bj).NE.0) aS2d(I,OB_Jn(I,bi,bj)+1,bi,bj)=0.
          IF (OB_Js(I,bi,bj).NE.0) aS2d(I,OB_Js(I,bi,bj)+1,bi,bj)=0.
          IF (OB_Js(I,bi,bj).NE.0) aS2d(I,OB_Js(I,bi,bj),bi,bj)=0.
         ENDDO
         DO J=1,sNy
          IF (OB_Ie(J,bi,bj).NE.0) aW2d(OB_Ie(J,bi,bj),J,bi,bj)=0.
          IF (OB_Ie(J,bi,bj).NE.0) aW2d(OB_Ie(J,bi,bj)+1,J,bi,bj)=0.
          IF (OB_Iw(J,bi,bj).NE.0) aW2d(OB_Iw(J,bi,bj)+1,J,bi,bj)=0.
          IF (OB_Iw(J,bi,bj).NE.0) aW2d(OB_Iw(J,bi,bj),J,bi,bj)=0.
         ENDDO
        ENDIF
#endif
        DO J=1,sNy
         DO I=1,sNx
          myNorm = MAX(ABS(aW2d(I,J,bi,bj)),myNorm)
          myNorm = MAX(ABS(aS2d(I,J,bi,bj)),myNorm)
         ENDDO
        ENDDO
       ENDDO
      ENDDO
      _GLOBAL_MAX_R4( myNorm, myThid )
      IF ( myNorm .NE. 0. _d 0 ) THEN
       myNorm = 1. _d 0/myNorm
      ELSE
       myNorm = 1. _d 0
      ENDIF
      DO bj=myByLo(myThid),myByHi(myThid)
       DO bi=myBxLo(myThid),myBxHi(myThid)
        DO J=1,sNy
         DO I=1,sNx
          aW2d(I,J,bi,bj) = aW2d(I,J,bi,bj)*myNorm
          aS2d(I,J,bi,bj) = aS2d(I,J,bi,bj)*myNorm
         ENDDO
        ENDDO
       ENDDO
      ENDDO
      
C--   Update overlap regions
CcnhDebugStarts
C     CALL PLOT_FIELD_XYRS( aW2d, 'AW2D INI_CG2D.1' , 1, myThid )
C     CALL PLOT_FIELD_XYRS( aS2d, 'AS2D INI_CG2D.1' , 1, myThid )
CcnhDebugEnds
c     _EXCH_XY_R4(aW2d, myThid)
c     _EXCH_XY_R4(aS2d, myThid)
      CALL EXCH_UV_XY_RS(aW2d,aS2d,.FALSE.,myThid)
CcnhDebugStarts
C     CALL PLOT_FIELD_XYRS( aW2d, 'AW2D INI_CG2D.2' , 1, myThid )
C     CALL PLOT_FIELD_XYRS( aS2d, 'AS2D INI_CG2D.2' , 1, myThid )
CcnhDebugEnds

      _BEGIN_MASTER(myThid)
C-- set global parameter in common block:
      cg2dNorm = myNorm
C-- Define the solver tolerance in the appropriate Unit :
      cg2dNormaliseRHS = cg2dTargetResWunit.LE.0.
      IF (cg2dNormaliseRHS) THEN
C-  when using a normalisation of RHS, tolerance has no unit => no conversion
        cg2dTolerance = cg2dTargetResidual
      ELSE
C-  convert Target-Residual (in W unit) to cg2d-solver residual unit [m^2/s^2]
        cg2dTolerance = cg2dNorm * cg2dTargetResWunit
     &                           * globalArea / deltaTmom
      ENDIF
      _END_MASTER(myThid)

CcnhDebugStarts
      _BEGIN_MASTER( myThid )
       WRITE(msgBuf,'(2A,1PE23.16)') 'INI_CG2D: ',
     &      'CG2D normalisation factor = ', cg2dNorm
       CALL PRINT_MESSAGE( msgBuf,standardMessageUnit,SQUEEZE_RIGHT,1)
       IF (.NOT.cg2dNormaliseRHS) THEN
        WRITE(msgBuf,'(2A,1PE22.15,A,1PE16.10,A)') 'INI_CG2D: ',
     &      'cg2dTolerance =', cg2dTolerance, ' (Area=',globalArea,')'
        CALL PRINT_MESSAGE(msgBuf,standardMessageUnit,SQUEEZE_RIGHT,1)
       ENDIF
       WRITE(msgBuf,*) ' '
       CALL PRINT_MESSAGE( msgBuf,standardMessageUnit,SQUEEZE_RIGHT,1)
      _END_MASTER( myThid )
CcnhDebugEnds
     
C--   Initialise preconditioner
C     Note. 20th May 1998
C           I made a weird discovery! In the model paper we argue
C           for the form of the preconditioner used here ( see
C           A Finite-volume, Incompressible Navier-Stokes Model
C           ...., Marshall et. al ). The algebra gives a simple
C           0.5 factor for the averaging of ac and aCw to get a
C           symmettric pre-conditioner. By using a factor of 0.51
C           i.e. scaling the off-diagonal terms in the
C           preconditioner down slightly I managed to get the
C           number of iterations for convergence in a test case to
C           drop form 192 -> 134! Need to investigate this further!
C           For now I have introduced a parameter cg2dpcOffDFac which
C           defaults to 0.51 but can be set at runtime.
      DO bj=myByLo(myThid),myByHi(myThid)
       DO bi=myBxLo(myThid),myBxHi(myThid)
        DO J=1,sNy
         DO I=1,sNx
          pC(I,J,bi,bj) = 1. _d 0
          aC = -(
     &     aW2d(I,J,bi,bj) + aW2d(I+1,J  ,bi,bj)
     &    +aS2d(I,J,bi,bj) + aS2d(I  ,J+1,bi,bj)
     &    +freeSurfFac*myNorm*recip_Bo(I,J,bi,bj)* 
     &     rA(I,J,bi,bj)/deltaTMom/deltaTfreesurf
     &    )
          aCs = -(
     &     aW2d(I,J-1,bi,bj) + aW2d(I+1,J-1,bi,bj)
     &    +aS2d(I,J-1,bi,bj) + aS2d(I  ,J  ,bi,bj)
     &    +freeSurfFac*myNorm*recip_Bo(I,J-1,bi,bj)* 
     &     rA(I,J-1,bi,bj)/deltaTMom/deltaTfreesurf
     &    )
          aCw = -(
     &     aW2d(I-1,J,bi,bj) + aW2d(I  ,J  ,bi,bj)
     &    +aS2d(I-1,J,bi,bj) + aS2d(I-1,J+1,bi,bj)
     &    +freeSurfFac*myNorm*recip_Bo(I-1,J,bi,bj)* 
     &     rA(I-1,J,bi,bj)/deltaTMom/deltaTfreesurf
     &    )
          IF ( aC .EQ. 0. ) THEN
            pC(I,J,bi,bj) = 1. _d 0
          ELSE
           pC(I,J,bi,bj) =  1. _d 0 / aC
          ENDIF
          IF ( aC + aCw .EQ. 0. ) THEN
           pW(I,J,bi,bj) = 0.
          ELSE
           pW(I,J,bi,bj) = 
     &     -aW2d(I  ,J  ,bi,bj)/((cg2dpcOffDFac *(aCw+aC))**2 )
          ENDIF
          IF ( aC + aCs .EQ. 0. ) THEN
           pS(I,J,bi,bj) = 0.
          ELSE
           pS(I,J,bi,bj) =
     &     -aS2d(I  ,J  ,bi,bj)/((cg2dpcOffDFac *(aCs+aC))**2 )
          ENDIF
C         pC(I,J,bi,bj) = 1.
C         pW(I,J,bi,bj) = 0.
C         pS(I,J,bi,bj) = 0.
         ENDDO
        ENDDO
       ENDDO
      ENDDO
C--   Update overlap regions
      _EXCH_XY_R4(pC, myThid)
c     _EXCH_XY_R4(pW, myThid)
c     _EXCH_XY_R4(pS, myThid)
      CALL EXCH_UV_XY_RS(pW,pS,.FALSE.,myThid)
CcnhDebugStarts
C     CALL PLOT_FIELD_XYRS( pC, 'pC   INI_CG2D.2' , 1, myThid )
C     CALL PLOT_FIELD_XYRS( pW, 'pW   INI_CG2D.2' , 1, myThid )
C     CALL PLOT_FIELD_XYRS( pS, 'pS   INI_CG2D.2' , 1, myThid )
CcnhDebugEnds

      RETURN
      END
1	jmc	1.44	C $Header: /u/gcmpack/MITgcm/model/src/ini_cg2d.F,v 1.43 2005/07/20 22:33:02 jmc Exp $
2	jmc	1.30	C $Name: $
3	cnh	1.1
4	edhill	1.42	#include "PACKAGES_CONFIG.h"
5	adcroft	1.13	#include "CPP_OPTIONS.h"
6	cnh	1.1
7	cnh	1.37	CBOP
8			C !ROUTINE: INI_CG2D
9			C !INTERFACE:
10	cnh	1.1	SUBROUTINE INI_CG2D( myThid )
11	cnh	1.37
12			C !DESCRIPTION: \bv
13			C ==========================================================
14			C \| SUBROUTINE INI_CG2D
15			C \| o Initialise 2d conjugate gradient solver operators.
16			C ==========================================================
17			C \| These arrays are purely a function of the basin geom.
18			C \| We set then here once and them use then repeatedly.
19			C ==========================================================
20			C \ev
21
22			C !USES:
23	adcroft	1.23	IMPLICIT NONE
24	cnh	1.1	C === Global variables ===
25			#include "SIZE.h"
26			#include "EEPARAMS.h"
27			#include "PARAMS.h"
28			#include "GRID.h"
29	jmc	1.31	#include "SURFACE.h"
30	adcroft	1.34	#include "CG2D.h"
31	adcroft	1.26	#ifdef ALLOW_OBCS
32	adcroft	1.22	#include "OBCS.h"
33	adcroft	1.26	#endif
34	cnh	1.1
35	cnh	1.37	C !INPUT/OUTPUT PARAMETERS:
36	cnh	1.1	C === Routine arguments ===
37			C myThid - Thread no. that called this routine.
38			INTEGER myThid
39
40	cnh	1.37	C !LOCAL VARIABLES:
41	cnh	1.1	C === Local variables ===
42			C xG, yG - Global coordinate location.
43			C zG
44			C iG, jG - Global coordinate index
45			C bi,bj - Loop counters
46			C faceArea - Temporary used to hold cell face areas.
47			C I,J,K
48	adcroft	1.34	C myNorm - Work variable used in calculating normalisation factor
49			C sumArea - Work variable used to compute the total Domain Area
50	cnh	1.1	CHARACTER*(MAX_LEN_MBUF) msgBuf
51			INTEGER bi, bj
52			INTEGER I, J, K
53	cnh	1.7	_RL faceArea
54	cnh	1.15	_RS myNorm
55	cnh	1.4	_RL aC, aCw, aCs
56	cnh	1.37	CEOP
57	jmc	1.38
58			C-- Initialize arrays in common blocs (CG2D.h) ; not really necessary
59			C but safer when EXCH do not fill all the overlap regions.
60			DO bj=myByLo(myThid),myByHi(myThid)
61			DO bi=myBxLo(myThid),myBxHi(myThid)
62			DO J=1-OLy,sNy+OLy
63			DO I=1-OLx,sNx+OLx
64			aW2d(I,J,bi,bj) = 0. _d 0
65			aS2d(I,J,bi,bj) = 0. _d 0
66			pW(I,J,bi,bj) = 0. _d 0
67			pS(I,J,bi,bj) = 0. _d 0
68			pC(I,J,bi,bj) = 0. _d 0
69			cg2d_q(I,J,bi,bj) = 0. _d 0
70			ENDDO
71			ENDDO
72			DO J=1-1,sNy+1
73			DO I=1-1,sNx+1
74			cg2d_r(I,J,bi,bj) = 0. _d 0
75			cg2d_s(I,J,bi,bj) = 0. _d 0
76			ENDDO
77			ENDDO
78			ENDDO
79			ENDDO
80	jmc	1.31
81	cnh	1.1	C-- Initialise laplace operator
82			C aW2d: integral in Z Ax/dX
83			C aS2d: integral in Z Ay/dY
84			myNorm = 0. _d 0
85			DO bj=myByLo(myThid),myByHi(myThid)
86			DO bi=myBxLo(myThid),myBxHi(myThid)
87			DO J=1,sNy
88			DO I=1,sNx
89			aW2d(I,J,bi,bj) = 0. _d 0
90			aS2d(I,J,bi,bj) = 0. _d 0
91			ENDDO
92			ENDDO
93	cnh	1.17	DO K=1,Nr
94	cnh	1.1	DO J=1,sNy
95			DO I=1,sNx
96	cnh	1.20	faceArea = _dyG(I,J,bi,bj)*drF(K)
97			& *_hFacW(I,J,K,bi,bj)
98	cnh	1.1	aW2d(I,J,bi,bj) = aW2d(I,J,bi,bj) +
99	jmc	1.32	& implicSurfPress*implicDiv2DFlow
100			& faceArearecip_dxC(I,J,bi,bj)
101	cnh	1.20	faceArea = _dxG(I,J,bi,bj)*drF(K)
102			& *_hFacS(I,J,K,bi,bj)
103	cnh	1.1	aS2d(I,J,bi,bj) = aS2d(I,J,bi,bj) +
104	jmc	1.32	& implicSurfPress*implicDiv2DFlow
105			& faceArearecip_dyC(I,J,bi,bj)
106	cnh	1.1	ENDDO
107			ENDDO
108			ENDDO
109	adcroft	1.26	#ifdef ALLOW_OBCS
110	adcroft	1.28	IF (useOBCS) THEN
111	adcroft	1.22	DO I=1,sNx
112			IF (OB_Jn(I,bi,bj).NE.0) aS2d(I,OB_Jn(I,bi,bj),bi,bj)=0.
113			IF (OB_Jn(I,bi,bj).NE.0) aS2d(I,OB_Jn(I,bi,bj)+1,bi,bj)=0.
114			IF (OB_Js(I,bi,bj).NE.0) aS2d(I,OB_Js(I,bi,bj)+1,bi,bj)=0.
115			IF (OB_Js(I,bi,bj).NE.0) aS2d(I,OB_Js(I,bi,bj),bi,bj)=0.
116			ENDDO
117			DO J=1,sNy
118			IF (OB_Ie(J,bi,bj).NE.0) aW2d(OB_Ie(J,bi,bj),J,bi,bj)=0.
119			IF (OB_Ie(J,bi,bj).NE.0) aW2d(OB_Ie(J,bi,bj)+1,J,bi,bj)=0.
120			IF (OB_Iw(J,bi,bj).NE.0) aW2d(OB_Iw(J,bi,bj)+1,J,bi,bj)=0.
121			IF (OB_Iw(J,bi,bj).NE.0) aW2d(OB_Iw(J,bi,bj),J,bi,bj)=0.
122			ENDDO
123			ENDIF
124	adcroft	1.26	#endif
125	cnh	1.1	DO J=1,sNy
126			DO I=1,sNx
127			myNorm = MAX(ABS(aW2d(I,J,bi,bj)),myNorm)
128			myNorm = MAX(ABS(aS2d(I,J,bi,bj)),myNorm)
129			ENDDO
130			ENDDO
131			ENDDO
132			ENDDO
133	adcroft	1.25	_GLOBAL_MAX_R4( myNorm, myThid )
134			IF ( myNorm .NE. 0. _d 0 ) THEN
135			myNorm = 1. _d 0/myNorm
136	cnh	1.1	ELSE
137			myNorm = 1. _d 0
138			ENDIF
139			DO bj=myByLo(myThid),myByHi(myThid)
140			DO bi=myBxLo(myThid),myBxHi(myThid)
141			DO J=1,sNy
142			DO I=1,sNx
143			aW2d(I,J,bi,bj) = aW2d(I,J,bi,bj)*myNorm
144			aS2d(I,J,bi,bj) = aS2d(I,J,bi,bj)*myNorm
145			ENDDO
146			ENDDO
147			ENDDO
148			ENDDO
149
150			C-- Update overlap regions
151			CcnhDebugStarts
152	cnh	1.14	C CALL PLOT_FIELD_XYRS( aW2d, 'AW2D INI_CG2D.1' , 1, myThid )
153			C CALL PLOT_FIELD_XYRS( aS2d, 'AS2D INI_CG2D.1' , 1, myThid )
154	cnh	1.1	CcnhDebugEnds
155	adcroft	1.34	c _EXCH_XY_R4(aW2d, myThid)
156			c _EXCH_XY_R4(aS2d, myThid)
157			CALL EXCH_UV_XY_RS(aW2d,aS2d,.FALSE.,myThid)
158	cnh	1.1	CcnhDebugStarts
159	adcroft	1.24	C CALL PLOT_FIELD_XYRS( aW2d, 'AW2D INI_CG2D.2' , 1, myThid )
160			C CALL PLOT_FIELD_XYRS( aS2d, 'AS2D INI_CG2D.2' , 1, myThid )
161	cnh	1.1	CcnhDebugEnds
162
163	jmc	1.44	_BEGIN_MASTER(myThid)
164			C-- set global parameter in common block:
165			cg2dNorm = myNorm
166	adcroft	1.34	C-- Define the solver tolerance in the appropriate Unit :
167	jmc	1.43	cg2dNormaliseRHS = cg2dTargetResWunit.LE.0.
168	adcroft	1.34	IF (cg2dNormaliseRHS) THEN
169			C- when using a normalisation of RHS, tolerance has no unit => no conversion
170			cg2dTolerance = cg2dTargetResidual
171			ELSE
172			C- convert Target-Residual (in W unit) to cg2d-solver residual unit [m^2/s^2]
173			cg2dTolerance = cg2dNorm * cg2dTargetResWunit
174	jmc	1.43	& * globalArea / deltaTmom
175	adcroft	1.34	ENDIF
176	jmc	1.44	_END_MASTER(myThid)
177	jmc	1.43
178			CcnhDebugStarts
179			_BEGIN_MASTER( myThid )
180			WRITE(msgBuf,'(2A,1PE23.16)') 'INI_CG2D: ',
181			& 'CG2D normalisation factor = ', cg2dNorm
182			CALL PRINT_MESSAGE( msgBuf,standardMessageUnit,SQUEEZE_RIGHT,1)
183			IF (.NOT.cg2dNormaliseRHS) THEN
184			WRITE(msgBuf,'(2A,1PE22.15,A,1PE16.10,A)') 'INI_CG2D: ',
185			& 'cg2dTolerance =', cg2dTolerance, ' (Area=',globalArea,')'
186			CALL PRINT_MESSAGE(msgBuf,standardMessageUnit,SQUEEZE_RIGHT,1)
187			ENDIF
188			WRITE(msgBuf,*) ' '
189			CALL PRINT_MESSAGE( msgBuf,standardMessageUnit,SQUEEZE_RIGHT,1)
190			_END_MASTER( myThid )
191			CcnhDebugEnds
192	adcroft	1.34
193	cnh	1.1	C-- Initialise preconditioner
194	cnh	1.4	C Note. 20th May 1998
195			C I made a weird discovery! In the model paper we argue
196			C for the form of the preconditioner used here ( see
197			C A Finite-volume, Incompressible Navier-Stokes Model
198			C ...., Marshall et. al ). The algebra gives a simple
199			C 0.5 factor for the averaging of ac and aCw to get a
200			C symmettric pre-conditioner. By using a factor of 0.51
201			C i.e. scaling the off-diagonal terms in the
202			C preconditioner down slightly I managed to get the
203			C number of iterations for convergence in a test case to
204			C drop form 192 -> 134! Need to investigate this further!
205			C For now I have introduced a parameter cg2dpcOffDFac which
206			C defaults to 0.51 but can be set at runtime.
207	cnh	1.1	DO bj=myByLo(myThid),myByHi(myThid)
208			DO bi=myBxLo(myThid),myBxHi(myThid)
209			DO J=1,sNy
210			DO I=1,sNx
211			pC(I,J,bi,bj) = 1. _d 0
212	cnh	1.4	aC = -(
213			& aW2d(I,J,bi,bj) + aW2d(I+1,J ,bi,bj)
214	adcroft	1.24	& +aS2d(I,J,bi,bj) + aS2d(I ,J+1,bi,bj)
215	jmc	1.32	& +freeSurfFacmyNormrecip_Bo(I,J,bi,bj)*
216	adcroft	1.39	& rA(I,J,bi,bj)/deltaTMom/deltaTfreesurf
217	cnh	1.4	& )
218			aCs = -(
219			& aW2d(I,J-1,bi,bj) + aW2d(I+1,J-1,bi,bj)
220			& +aS2d(I,J-1,bi,bj) + aS2d(I ,J ,bi,bj)
221	jmc	1.32	& +freeSurfFacmyNormrecip_Bo(I,J-1,bi,bj)*
222	adcroft	1.39	& rA(I,J-1,bi,bj)/deltaTMom/deltaTfreesurf
223	cnh	1.4	& )
224			aCw = -(
225			& aW2d(I-1,J,bi,bj) + aW2d(I ,J ,bi,bj)
226			& +aS2d(I-1,J,bi,bj) + aS2d(I-1,J+1,bi,bj)
227	jmc	1.32	& +freeSurfFacmyNormrecip_Bo(I-1,J,bi,bj)*
228	adcroft	1.39	& rA(I-1,J,bi,bj)/deltaTMom/deltaTfreesurf
229	cnh	1.4	& )
230			IF ( aC .EQ. 0. ) THEN
231	adcroft	1.27	pC(I,J,bi,bj) = 1. _d 0
232	cnh	1.4	ELSE
233			pC(I,J,bi,bj) = 1. _d 0 / aC
234			ENDIF
235			IF ( aC + aCw .EQ. 0. ) THEN
236			pW(I,J,bi,bj) = 0.
237			ELSE
238			pW(I,J,bi,bj) =
239			& -aW2d(I ,J ,bi,bj)/((cg2dpcOffDFac (aCw+aC))*2 )
240			ENDIF
241			IF ( aC + aCs .EQ. 0. ) THEN
242			pS(I,J,bi,bj) = 0.
243			ELSE
244			pS(I,J,bi,bj) =
245			& -aS2d(I ,J ,bi,bj)/((cg2dpcOffDFac (aCs+aC))*2 )
246			ENDIF
247	cnh	1.6	C pC(I,J,bi,bj) = 1.
248			C pW(I,J,bi,bj) = 0.
249			C pS(I,J,bi,bj) = 0.
250	cnh	1.1	ENDDO
251			ENDDO
252			ENDDO
253			ENDDO
254			C-- Update overlap regions
255			_EXCH_XY_R4(pC, myThid)
256	adcroft	1.34	c _EXCH_XY_R4(pW, myThid)
257			c _EXCH_XY_R4(pS, myThid)
258			CALL EXCH_UV_XY_RS(pW,pS,.FALSE.,myThid)
259	cnh	1.18	CcnhDebugStarts
260	adcroft	1.24	C CALL PLOT_FIELD_XYRS( pC, 'pC INI_CG2D.2' , 1, myThid )
261			C CALL PLOT_FIELD_XYRS( pW, 'pW INI_CG2D.2' , 1, myThid )
262			C CALL PLOT_FIELD_XYRS( pS, 'pS INI_CG2D.2' , 1, myThid )
263	cnh	1.18	CcnhDebugEnds
264	cnh	1.1
265			RETURN
266			END