model/src/ini_cg2d.F

C $Header: /u/gcmpack/MITgcm/model/src/ini_cg2d.F,v 1.46 2009/04/28 18:01:14 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     bi,bj  :: tile indices
C     I,J,K  :: Loop counters
C     faceArea - Temporary used to hold cell face areas.
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, ks
      _RL     faceArea
      _RS     myNorm
      _RS     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
          aC2d(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
         ENDDO
        ENDDO
        DO J=1-1,sNy+1
         DO I=1-1,sNx+1
          cg2d_q(I,J,bi,bj) = 0. _d 0
          cg2d_r(I,J,bi,bj) = 0. _d 0
          cg2d_s(I,J,bi,bj) = 0. _d 0
#ifdef ALLOW_CG2D_NSA
          cg2d_z(I,J,bi,bj) = 0. _d 0
#endif /* ALLOW_CG2D_NSA */
         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
C  deep-model: *deepFacC (faceArea), /deepFacC (recip_dx,y): => no net effect
           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_RS( 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
      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
          ks = ksurfC(I,J,bi,bj)
          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)*deepFac2F(ks)
     &                *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)*deepFac2F(ks)
     &                *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)*deepFac2F(ks)
     &                *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-    store solver main diagonal :
          aC2d(I,J,bi,bj) = aC
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
      CALL EXCH_XY_RS( pC, 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	1.47	C $Header: /u/gcmpack/MITgcm/model/src/ini_cg2d.F,v 1.46 2009/04/28 18:01:14 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	jmc	1.47	C \| SUBROUTINE INI_CG2D
15			C \| o Initialise 2d conjugate gradient solver operators.
16	cnh	1.37	C ==========================================================
17	jmc	1.47	C \| These arrays are purely a function of the basin geom.
18			C \| We set then here once and them use then repeatedly.
19	cnh	1.37	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	jmc	1.45	C bi,bj :: tile indices
43			C I,J,K :: Loop counters
44	cnh	1.1	C faceArea - Temporary used to hold cell face areas.
45	adcroft	1.34	C myNorm - Work variable used in calculating normalisation factor
46	jmc	1.45	C sumArea - Work variable used to compute the total Domain Area
47	cnh	1.1	CHARACTER*(MAX_LEN_MBUF) msgBuf
48			INTEGER bi, bj
49	jmc	1.45	INTEGER I, J, K, ks
50	cnh	1.7	_RL faceArea
51	cnh	1.15	_RS myNorm
52	jmc	1.45	_RS aC, aCw, aCs
53	cnh	1.37	CEOP
54	jmc	1.38
55	jmc	1.45	C-- Initialize arrays in common blocs (CG2D.h) ; not really necessary
56	jmc	1.38	C but safer when EXCH do not fill all the overlap regions.
57			DO bj=myByLo(myThid),myByHi(myThid)
58			DO bi=myBxLo(myThid),myBxHi(myThid)
59			DO J=1-OLy,sNy+OLy
60			DO I=1-OLx,sNx+OLx
61			aW2d(I,J,bi,bj) = 0. _d 0
62			aS2d(I,J,bi,bj) = 0. _d 0
63	jmc	1.45	aC2d(I,J,bi,bj) = 0. _d 0
64	jmc	1.38	pW(I,J,bi,bj) = 0. _d 0
65			pS(I,J,bi,bj) = 0. _d 0
66			pC(I,J,bi,bj) = 0. _d 0
67			ENDDO
68			ENDDO
69			DO J=1-1,sNy+1
70			DO I=1-1,sNx+1
71	jmc	1.47	cg2d_q(I,J,bi,bj) = 0. _d 0
72	jmc	1.38	cg2d_r(I,J,bi,bj) = 0. _d 0
73			cg2d_s(I,J,bi,bj) = 0. _d 0
74	jmc	1.47	#ifdef ALLOW_CG2D_NSA
75			cg2d_z(I,J,bi,bj) = 0. _d 0
76			#endif /* ALLOW_CG2D_NSA */
77	jmc	1.38	ENDDO
78			ENDDO
79			ENDDO
80			ENDDO
81	jmc	1.31
82	cnh	1.1	C-- Initialise laplace operator
83			C aW2d: integral in Z Ax/dX
84			C aS2d: integral in Z Ay/dY
85			myNorm = 0. _d 0
86			DO bj=myByLo(myThid),myByHi(myThid)
87			DO bi=myBxLo(myThid),myBxHi(myThid)
88			DO J=1,sNy
89			DO I=1,sNx
90			aW2d(I,J,bi,bj) = 0. _d 0
91			aS2d(I,J,bi,bj) = 0. _d 0
92			ENDDO
93			ENDDO
94	cnh	1.17	DO K=1,Nr
95	cnh	1.1	DO J=1,sNy
96			DO I=1,sNx
97	jmc	1.45	C deep-model: *deepFacC (faceArea), /deepFacC (recip_dx,y): => no net effect
98	cnh	1.20	faceArea = _dyG(I,J,bi,bj)*drF(K)
99			& *_hFacW(I,J,K,bi,bj)
100	jmc	1.45	aW2d(I,J,bi,bj) = aW2d(I,J,bi,bj)
101			& + implicSurfPress*implicDiv2DFlow
102			& faceArearecip_dxC(I,J,bi,bj)
103	cnh	1.20	faceArea = _dxG(I,J,bi,bj)*drF(K)
104			& *_hFacS(I,J,K,bi,bj)
105	jmc	1.45	aS2d(I,J,bi,bj) = aS2d(I,J,bi,bj)
106			& + implicSurfPress*implicDiv2DFlow
107			& faceArearecip_dyC(I,J,bi,bj)
108	cnh	1.1	ENDDO
109			ENDDO
110			ENDDO
111	adcroft	1.26	#ifdef ALLOW_OBCS
112	adcroft	1.28	IF (useOBCS) THEN
113	adcroft	1.22	DO I=1,sNx
114			IF (OB_Jn(I,bi,bj).NE.0) aS2d(I,OB_Jn(I,bi,bj),bi,bj)=0.
115			IF (OB_Jn(I,bi,bj).NE.0) aS2d(I,OB_Jn(I,bi,bj)+1,bi,bj)=0.
116			IF (OB_Js(I,bi,bj).NE.0) aS2d(I,OB_Js(I,bi,bj)+1,bi,bj)=0.
117			IF (OB_Js(I,bi,bj).NE.0) aS2d(I,OB_Js(I,bi,bj),bi,bj)=0.
118			ENDDO
119			DO J=1,sNy
120			IF (OB_Ie(J,bi,bj).NE.0) aW2d(OB_Ie(J,bi,bj),J,bi,bj)=0.
121			IF (OB_Ie(J,bi,bj).NE.0) aW2d(OB_Ie(J,bi,bj)+1,J,bi,bj)=0.
122			IF (OB_Iw(J,bi,bj).NE.0) aW2d(OB_Iw(J,bi,bj)+1,J,bi,bj)=0.
123			IF (OB_Iw(J,bi,bj).NE.0) aW2d(OB_Iw(J,bi,bj),J,bi,bj)=0.
124			ENDDO
125			ENDIF
126	adcroft	1.26	#endif
127	cnh	1.1	DO J=1,sNy
128			DO I=1,sNx
129			myNorm = MAX(ABS(aW2d(I,J,bi,bj)),myNorm)
130			myNorm = MAX(ABS(aS2d(I,J,bi,bj)),myNorm)
131			ENDDO
132			ENDDO
133			ENDDO
134			ENDDO
135	jmc	1.46	_GLOBAL_MAX_RS( myNorm, myThid )
136	adcroft	1.25	IF ( myNorm .NE. 0. _d 0 ) THEN
137			myNorm = 1. _d 0/myNorm
138	cnh	1.1	ELSE
139			myNorm = 1. _d 0
140			ENDIF
141			DO bj=myByLo(myThid),myByHi(myThid)
142			DO bi=myBxLo(myThid),myBxHi(myThid)
143			DO J=1,sNy
144			DO I=1,sNx
145			aW2d(I,J,bi,bj) = aW2d(I,J,bi,bj)*myNorm
146			aS2d(I,J,bi,bj) = aS2d(I,J,bi,bj)*myNorm
147			ENDDO
148			ENDDO
149			ENDDO
150			ENDDO
151	jmc	1.45
152	cnh	1.1	C-- Update overlap regions
153			CcnhDebugStarts
154	cnh	1.14	C CALL PLOT_FIELD_XYRS( aW2d, 'AW2D INI_CG2D.1' , 1, myThid )
155			C CALL PLOT_FIELD_XYRS( aS2d, 'AS2D INI_CG2D.1' , 1, myThid )
156	cnh	1.1	CcnhDebugEnds
157	jmc	1.47	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	jmc	1.45
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	jmc	1.45	ks = ksurfC(I,J,bi,bj)
212	cnh	1.1	pC(I,J,bi,bj) = 1. _d 0
213	cnh	1.4	aC = -(
214			& aW2d(I,J,bi,bj) + aW2d(I+1,J ,bi,bj)
215	adcroft	1.24	& +aS2d(I,J,bi,bj) + aS2d(I ,J+1,bi,bj)
216	jmc	1.45	& +freeSurfFacmyNormrecip_Bo(I,J,bi,bj)*deepFac2F(ks)
217			& *rA(I,J,bi,bj)/deltaTMom/deltaTfreesurf
218	cnh	1.4	& )
219			aCs = -(
220			& aW2d(I,J-1,bi,bj) + aW2d(I+1,J-1,bi,bj)
221			& +aS2d(I,J-1,bi,bj) + aS2d(I ,J ,bi,bj)
222	jmc	1.45	& +freeSurfFacmyNormrecip_Bo(I,J-1,bi,bj)*deepFac2F(ks)
223			& *rA(I,J-1,bi,bj)/deltaTMom/deltaTfreesurf
224	cnh	1.4	& )
225			aCw = -(
226			& aW2d(I-1,J,bi,bj) + aW2d(I ,J ,bi,bj)
227			& +aS2d(I-1,J,bi,bj) + aS2d(I-1,J+1,bi,bj)
228	jmc	1.45	& +freeSurfFacmyNormrecip_Bo(I-1,J,bi,bj)*deepFac2F(ks)
229			& *rA(I-1,J,bi,bj)/deltaTMom/deltaTfreesurf
230	cnh	1.4	& )
231			IF ( aC .EQ. 0. ) THEN
232	adcroft	1.27	pC(I,J,bi,bj) = 1. _d 0
233	cnh	1.4	ELSE
234			pC(I,J,bi,bj) = 1. _d 0 / aC
235			ENDIF
236			IF ( aC + aCw .EQ. 0. ) THEN
237			pW(I,J,bi,bj) = 0.
238			ELSE
239	jmc	1.45	pW(I,J,bi,bj) =
240	cnh	1.4	& -aW2d(I ,J ,bi,bj)/((cg2dpcOffDFac (aCw+aC))*2 )
241			ENDIF
242			IF ( aC + aCs .EQ. 0. ) THEN
243			pS(I,J,bi,bj) = 0.
244			ELSE
245			pS(I,J,bi,bj) =
246			& -aS2d(I ,J ,bi,bj)/((cg2dpcOffDFac (aCs+aC))*2 )
247			ENDIF
248	jmc	1.45	C- store solver main diagonal :
249			aC2d(I,J,bi,bj) = aC
250	cnh	1.6	C pC(I,J,bi,bj) = 1.
251			C pW(I,J,bi,bj) = 0.
252			C pS(I,J,bi,bj) = 0.
253	cnh	1.1	ENDDO
254			ENDDO
255			ENDDO
256			ENDDO
257			C-- Update overlap regions
258	jmc	1.47	CALL EXCH_XY_RS( pC, myThid )
259			CALL EXCH_UV_XY_RS( pW, pS, .FALSE., myThid )
260	cnh	1.18	CcnhDebugStarts
261	adcroft	1.24	C CALL PLOT_FIELD_XYRS( pC, 'pC INI_CG2D.2' , 1, myThid )
262			C CALL PLOT_FIELD_XYRS( pW, 'pW INI_CG2D.2' , 1, myThid )
263			C CALL PLOT_FIELD_XYRS( pS, 'pS INI_CG2D.2' , 1, myThid )
264	cnh	1.18	CcnhDebugEnds
265	cnh	1.1
266			RETURN
267			END