| 1 | C $Header: /u/gcmpack/MITgcm/pkg/seaice/seaice_calc_strainrates.F,v 1.13 2009/06/03 08:48:07 mlosch Exp $ | 
| 2 | C $Name:  $ | 
| 3 |  | 
| 4 | #include "SEAICE_OPTIONS.h" | 
| 5 |  | 
| 6 | CStartOfInterface | 
| 7 | SUBROUTINE SEAICE_CALC_STRAINRATES( | 
| 8 | I     uFld, vFld, | 
| 9 | O     e11Loc, e22Loc, e12Loc, | 
| 10 | I     iStep, myTime, myIter, myThid ) | 
| 11 | C     /==========================================================\ | 
| 12 | C     | SUBROUTINE  SEAICE_CALC_STRAINRATES                      | | 
| 13 | C     | o compute strain rates from ice velocities               | | 
| 14 | C     |==========================================================| | 
| 15 | C     | written by Martin Losch, Apr 2007                        | | 
| 16 | C     \==========================================================/ | 
| 17 | IMPLICIT NONE | 
| 18 |  | 
| 19 | C     === Global variables === | 
| 20 | #include "SIZE.h" | 
| 21 | #include "EEPARAMS.h" | 
| 22 | #include "PARAMS.h" | 
| 23 | #include "GRID.h" | 
| 24 | #include "SEAICE_PARAMS.h" | 
| 25 | #include "SEAICE.h" | 
| 26 |  | 
| 27 | #ifdef ALLOW_AUTODIFF_TAMC | 
| 28 | # include "tamc.h" | 
| 29 | #endif | 
| 30 |  | 
| 31 | C     === Routine arguments === | 
| 32 | C     iStep  :: Sub-time-step number | 
| 33 | C     myTime :: Simulation time | 
| 34 | C     myIter :: Simulation timestep number | 
| 35 | C     myThid :: My Thread Id. number | 
| 36 | INTEGER iStep | 
| 37 | _RL     myTime | 
| 38 | INTEGER myIter | 
| 39 | INTEGER myThid | 
| 40 | C     ice velocities | 
| 41 | _RL uFld   (1-Olx:sNx+Olx,1-Oly:sNy+Oly,nSx,nSy) | 
| 42 | _RL vFld   (1-Olx:sNx+Olx,1-Oly:sNy+Oly,nSx,nSy) | 
| 43 | C     strain rate tensor | 
| 44 | _RL e11Loc (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy) | 
| 45 | _RL e22Loc (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy) | 
| 46 | _RL e12Loc (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy) | 
| 47 | CEndOfInterface | 
| 48 |  | 
| 49 | #ifdef SEAICE_CGRID | 
| 50 | #ifdef SEAICE_ALLOW_DYNAMICS | 
| 51 | C     === Local variables === | 
| 52 | C     i,j,bi,bj - Loop counters | 
| 53 | INTEGER i, j, bi, bj | 
| 54 | C  hFacU, hFacV - determine the no-slip boundary condition | 
| 55 | INTEGER k | 
| 56 | _RS hFacU, hFacV, noSlipFac | 
| 57 |  | 
| 58 | k = 1 | 
| 59 | noSlipFac = 0. _d 0 | 
| 60 | IF ( SEAICE_no_slip ) noSlipFac = 1. _d 0 | 
| 61 | C | 
| 62 | #ifndef SEAICE_OLD_AND_BAD_DISCRETIZATION | 
| 63 | DO bj=myByLo(myThid),myByHi(myThid) | 
| 64 | DO bi=myBxLo(myThid),myBxHi(myThid) | 
| 65 | DO j=1-Oly,sNy+Oly-1 | 
| 66 | DO i=1-Olx,sNx+Olx-1 | 
| 67 | C     evaluate strain rates | 
| 68 | e11Loc(I,J,bi,bj) = _recip_dxF(I,J,bi,bj) * | 
| 69 | &         (uFld(I+1,J,bi,bj)-uFld(I,J,bi,bj)) | 
| 70 | &         +HALF* | 
| 71 | &         (vFld(I,J,bi,bj)+vFld(I,J+1,bi,bj)) | 
| 72 | &         * k2AtC(I,J,bi,bj) | 
| 73 | e22Loc(I,J,bi,bj) = _recip_dyF(I,J,bi,bj) * | 
| 74 | &         (vFld(I,J+1,bi,bj)-vFld(I,J,bi,bj)) | 
| 75 | &         +HALF* | 
| 76 | &         (uFld(I,J,bi,bj)+uFld(I+1,J,bi,bj)) | 
| 77 | &         * k1AtC(I,J,bi,bj) | 
| 78 | ENDDO | 
| 79 | ENDDO | 
| 80 | DO j=1-Oly+1,sNy+Oly | 
| 81 | DO i=1-Olx+1,sNx+Olx | 
| 82 | hFacU = _maskW(i,j,k,bi,bj) - _maskW(i,j-1,k,bi,bj) | 
| 83 | hFacV = _maskS(i,j,k,bi,bj) - _maskS(i-1,j,k,bi,bj) | 
| 84 | e12Loc(I,J,bi,bj) = HALF*( | 
| 85 | &           ( uFld(I,J,bi,bj) - uFld(I  ,J-1,bi,bj) ) | 
| 86 | &         * _recip_dyU(I,J,bi,bj) | 
| 87 | &         + ( vFld(I,J,bi,bj) - vFld(I-1,J  ,bi,bj) ) | 
| 88 | &         * _recip_dxV(I,J,bi,bj) | 
| 89 | &         - k1AtZ(I,J,bi,bj) | 
| 90 | &         * 0.5 _d 0 * (vFld(I,J,bi,bj)+vFld(I-1,J  ,bi,bj)) | 
| 91 | &         - k2AtZ(I,J,bi,bj) | 
| 92 | &         * 0.5 _d 0 * (uFld(I,J,bi,bj)+uFld(I  ,J-1,bi,bj)) | 
| 93 | &         ) | 
| 94 | &         *maskC(I  ,J  ,k,bi,bj)*maskC(I-1,J  ,k,bi,bj) | 
| 95 | &         *maskC(I  ,J-1,k,bi,bj)*maskC(I-1,J-1,k,bi,bj) | 
| 96 | &         + 2.0 _d 0 * noSlipFac * ( | 
| 97 | &           ( uFld(I,J,bi,bj) + uFld(I  ,J-1,bi,bj) ) | 
| 98 | &         * _recip_dyU(I,J,bi,bj) * hFacU | 
| 99 | &         + ( vFld(I,J,bi,bj) + vFld(I-1,J  ,bi,bj) ) | 
| 100 | &         * _recip_dxV(I,J,bi,bj) * hFacV | 
| 101 | &         ) | 
| 102 | C     no slip at the boundary implies u(j)+u(j-1)=0 and v(i)+v(i-1)=0 | 
| 103 | C     accross the boundary; this is already accomplished by masking so | 
| 104 | C     that the following lines are not necessary | 
| 105 | c$$$     &         - hFacV * k1AtZ(I,J,bi,bj) | 
| 106 | c$$$     &         * 0.5 _d 0 * (vFld(I,J,bi,bj)+vFld(I-1,J  ,bi,bj)) | 
| 107 | c$$$     &         - hFacU * k2AtZ(I,J,bi,bj) | 
| 108 | c$$$     &         * 0.5 _d 0 * (uFld(I,J,bi,bj)+uFld(I  ,J-1,bi,bj)) | 
| 109 | ENDDO | 
| 110 | ENDDO | 
| 111 |  | 
| 112 | c$$$        ENDIF | 
| 113 | ENDDO | 
| 114 | ENDDO | 
| 115 | #else | 
| 116 | C     this the old and incomplete discretization, here I also erroneously | 
| 117 | C     used finite-volumes to discretize the strain rates | 
| 118 | DO bj=myByLo(myThid),myByHi(myThid) | 
| 119 | DO bi=myBxLo(myThid),myBxHi(myThid) | 
| 120 | DO j=1-Oly,sNy+Oly-1 | 
| 121 | DO i=1-Olx,sNx+Olx-1 | 
| 122 | C     evaluate strain rates | 
| 123 | e11Loc(I,J,bi,bj) = _recip_dxF(I,J,bi,bj) * | 
| 124 | &         (uFld(I+1,J,bi,bj)-uFld(I,J,bi,bj)) | 
| 125 | &         -HALF* | 
| 126 | &         (vFld(I,J,bi,bj)+vFld(I,J+1,bi,bj)) | 
| 127 | &         * _tanPhiAtU(I,J,bi,bj)*recip_rSphere | 
| 128 | e22Loc(I,J,bi,bj) = _recip_dyF(I,J,bi,bj) * | 
| 129 | &         (vFld(I,J+1,bi,bj)-vFld(I,J,bi,bj)) | 
| 130 | C     one metric term is missing | 
| 131 | ENDDO | 
| 132 | ENDDO | 
| 133 | DO j=1-Oly+1,sNy+Oly | 
| 134 | DO i=1-Olx+1,sNx+Olx | 
| 135 | e12Loc(I,J,bi,bj) = HALF*( | 
| 136 | &         (uFld(I  ,J  ,bi,bj) * _dxC(I  ,J  ,bi,bj) | 
| 137 | &         -uFld(I  ,J-1,bi,bj) * _dxC(I  ,J-1,bi,bj) | 
| 138 | &         +vFld(I  ,J  ,bi,bj) * _dyC(I  ,J  ,bi,bj) | 
| 139 | &         -vFld(I-1,J  ,bi,bj) * _dyC(I-1,J  ,bi,bj)) | 
| 140 | &         * recip_rAz(I,J,bi,bj) | 
| 141 | &         + | 
| 142 | &         0.25 _d 0 * (uFld(I,J,bi,bj)+uFld(I  ,J-1,bi,bj)) | 
| 143 | &         * ( _tanPhiAtU(I,J,bi,bj) + _tanPhiAtU(I,J-1,bi,bj) ) | 
| 144 | &         *recip_rSphere | 
| 145 | &         ) | 
| 146 | &         *maskC(I  ,J  ,k,bi,bj)*maskC(I-1,J  ,k,bi,bj) | 
| 147 | &         *maskC(I  ,J-1,k,bi,bj)*maskC(I-1,J-1,k,bi,bj) | 
| 148 | C     one metric term is missing | 
| 149 | ENDDO | 
| 150 | ENDDO | 
| 151 | IF ( SEAICE_no_slip ) THEN | 
| 152 | C     no slip boundary conditions apply only to e12Loc | 
| 153 | DO j=1-Oly+1,sNy+Oly | 
| 154 | DO i=1-Olx+1,sNx+Olx | 
| 155 | hFacU = _maskW(i,j,k,bi,bj) - _maskW(i,j-1,k,bi,bj) | 
| 156 | hFacV = _maskS(i,j,k,bi,bj) - _maskS(i-1,j,k,bi,bj) | 
| 157 |  | 
| 158 | e12Loc(I,J,bi,bj) = e12Loc(I,J,bi,bj) | 
| 159 | &          + recip_rAz(i,j,bi,bj) * 2. _d 0 * | 
| 160 | &          ( hFacU * ( _dxC(i,j-1,bi,bj)*uFld(i,j  ,bi,bj) | 
| 161 | &                    + _dxC(i,j,  bi,bj)*uFld(i,j-1,bi,bj) ) | 
| 162 | &          + hFacV * ( _dyC(i-1,j,bi,bj)*vFld(i  ,j,bi,bj) | 
| 163 | &                    + _dyC(i,  j,bi,bj)*vFld(i-1,j,bi,bj) ) ) | 
| 164 | &         - hFacU | 
| 165 | &         * 0.25 _d 0 * (uFld(I,J,bi,bj)+uFld(I  ,J-1,bi,bj)) | 
| 166 | &         * ( _tanPhiAtU(I,J,bi,bj) + _tanPhiAtU(I,J-1,bi,bj) ) | 
| 167 | &         *recip_rSphere | 
| 168 | C     one metric term is missing | 
| 169 | ENDDO | 
| 170 | ENDDO | 
| 171 |  | 
| 172 | ENDIF | 
| 173 | ENDDO | 
| 174 | ENDDO | 
| 175 | #endif /* SEAICE_OLD_AND_BAD_DISCRETIZATION */ | 
| 176 | #endif /* SEAICE_ALLOW_DYNAMICS */ | 
| 177 | #endif /* SEAICE_CGRID */ | 
| 178 | RETURN | 
| 179 | END |