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C $Header: /u/gcmpack/MITgcm/pkg/seaice/seaice_calc_strainrates.F,v 1.8 2007/11/13 19:26:25 jmc Exp $ | 
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C $Name:  $ | 
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 | 
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#include "SEAICE_OPTIONS.h" | 
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 | 
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CStartOfInterface | 
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      SUBROUTINE SEAICE_CALC_STRAINRATES( | 
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     I     uFld, vFld, | 
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     O     e11, e22, e12, | 
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     I     kSize, iStep, myTime, myIter, myThid ) | 
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C     /==========================================================\ | 
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C     | SUBROUTINE  SEAICE_CALC_STRAINRATES                      | | 
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C     | o compute strain rates from ice velocities               | | 
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C     |==========================================================| | 
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C     | written by Martin Losch, Apr 2007                        | | 
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C     \==========================================================/ | 
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      IMPLICIT NONE | 
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 | 
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C     === Global variables === | 
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#include "SIZE.h" | 
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#include "EEPARAMS.h" | 
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#include "PARAMS.h" | 
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#include "GRID.h" | 
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#include "SEAICE_PARAMS.h" | 
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 | 
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#ifdef ALLOW_AUTODIFF_TAMC | 
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# include "tamc.h" | 
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#endif | 
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 | 
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C     === Routine arguments === | 
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C     iStep  :: Sub-time-step number | 
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C     myTime :: Simulation time | 
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C     myIter :: Simulation timestep number | 
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C     myThid :: My Thread Id. number | 
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C     kSize  :: length of 3rd dimension of velocity variables | 
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      INTEGER iStep | 
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      _RL     myTime | 
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      INTEGER myIter | 
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      INTEGER myThid | 
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      INTEGER kSize | 
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C     ice velocities | 
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      _RL uFld(1-Olx:sNx+Olx,1-Oly:sNy+Oly,kSize,nSx,nSy) | 
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      _RL vFld(1-Olx:sNx+Olx,1-Oly:sNy+Oly,kSize,nSx,nSy) | 
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C     strain rate tensor | 
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      _RL e11 (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy) | 
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      _RL e22 (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy) | 
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      _RL e12 (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy) | 
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CEndOfInterface | 
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 | 
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#ifdef SEAICE_CGRID | 
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#ifdef SEAICE_ALLOW_DYNAMICS | 
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C     === Local variables === | 
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C     i,j,bi,bj - Loop counters | 
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      INTEGER i, j, bi, bj | 
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C  hFacU, hFacV - determine the no-slip boundary condition | 
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      INTEGER k | 
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      _RS hFacU, hFacV | 
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 | 
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      k = 1 | 
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C | 
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      DO bj=myByLo(myThid),myByHi(myThid) | 
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       DO bi=myBxLo(myThid),myBxHi(myThid) | 
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        DO j=1-Oly,sNy+Oly-1 | 
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         DO i=1-Olx,sNx+Olx-1 | 
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C     evaluate strain rates | 
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          e11(I,J,bi,bj) = _recip_dxF(I,J,bi,bj) * | 
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     &         (uFld(I+1,J,1,bi,bj)-uFld(I,J,1,bi,bj)) | 
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     &         -HALF* | 
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     &         (vFld(I,J,1,bi,bj)+vFld(I,J+1,1,bi,bj)) | 
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     &         * _tanPhiAtU(I,J,bi,bj)*recip_rSphere | 
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          e22(I,J,bi,bj) = _recip_dyF(I,J,bi,bj) * | 
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     &         (vFld(I,J+1,1,bi,bj)-vFld(I,J,1,bi,bj)) | 
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C     one metric term is missing | 
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         ENDDO | 
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        ENDDO | 
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        DO j=1-Oly+1,sNy+Oly | 
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         DO i=1-Olx+1,sNx+Olx | 
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          e12(I,J,bi,bj) = HALF*( | 
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     &         (uFld(I  ,J  ,1,bi,bj) * _dxC(I  ,J  ,bi,bj) | 
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     &         -uFld(I  ,J-1,1,bi,bj) * _dxC(I  ,J-1,bi,bj) | 
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     &         +vFld(I  ,J  ,1,bi,bj) * _dyC(I  ,J  ,bi,bj) | 
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     &         -vFld(I-1,J  ,1,bi,bj) * _dyC(I-1,J  ,bi,bj)) | 
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     &         * recip_rAz(I,J,bi,bj) | 
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     &         + | 
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     &         0.25 _d 0 * (uFld(I,J,1,bi,bj)+uFld(I  ,J-1,1,bi,bj)) | 
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     &         * ( _tanPhiAtU(I,J,bi,bj) + _tanPhiAtU(I,J-1,bi,bj) ) | 
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     &         *recip_rSphere | 
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     &         ) | 
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     &         *maskC(I  ,J  ,k,bi,bj)*maskC(I-1,J  ,k,bi,bj) | 
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     &         *maskC(I  ,J-1,k,bi,bj)*maskC(I-1,J-1,k,bi,bj) | 
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C     one metric term is missing | 
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         ENDDO | 
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        ENDDO | 
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        IF ( SEAICE_no_slip ) THEN | 
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C     no slip boundary conditions apply only to e12 | 
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         DO j=1-Oly+1,sNy+Oly | 
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          DO i=1-Olx+1,sNx+Olx | 
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           hFacU = _maskW(i,j,k,bi,bj) - _maskW(i,j-1,k,bi,bj) | 
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           hFacV = _maskS(i,j,k,bi,bj) - _maskS(i-1,j,k,bi,bj) | 
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 | 
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           e12(I,J,bi,bj) = e12(I,J,bi,bj) | 
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     &          + recip_rAz(i,j,bi,bj) * | 
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     &          ( hFacU * ( _dxC(i,j-1,bi,bj)*uFld(i,j  ,1,bi,bj) | 
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     &                    + _dxC(i,j,  bi,bj)*uFld(i,j-1,1,bi,bj) ) | 
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     &          + hFacV * ( _dyC(i-1,j,bi,bj)*vFld(i  ,j,1,bi,bj) | 
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     &                    + _dyC(i,  j,bi,bj)*vFld(i-1,j,1,bi,bj) ) ) | 
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     &         - hFacU | 
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     &         * 0.25 _d 0 * (uFld(I,J,1,bi,bj)+uFld(I  ,J-1,1,bi,bj)) | 
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     &         * ( _tanPhiAtU(I,J,bi,bj) + _tanPhiAtU(I,J-1,bi,bj) ) | 
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     &         *recip_rSphere | 
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C     one metric term is missing | 
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          ENDDO | 
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         ENDDO | 
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 | 
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        ENDIF | 
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       ENDDO | 
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      ENDDO | 
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#endif /* SEAICE_ALLOW_DYNAMICS */ | 
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#endif /* SEAICE_CGRID */ | 
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      RETURN | 
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      END |