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C $Header: /u/gcmpack/MITgcm/model/src/calc_grid_angles.F,v 1.1 2011/12/25 22:24:35 jmc Exp $ |
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C $Name: $ |
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#include "CPP_OPTIONS.h" |
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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CBOP |
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C !ROUTINE: CALC_GRID_ANGLES |
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C !INTERFACE: |
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SUBROUTINE CALC_GRID_ANGLES( skipCalcAngleC, myThid ) |
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|
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C !DESCRIPTION: \bv |
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C *===================================================================* |
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C | SUBROUTINE CALC_GRID_ANGLES |
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C | o calculate the angle between geographical north and model grid |
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C | north, assuming that yG holds the geographical coordinates |
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C *===================================================================* |
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C \ev |
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|
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C !USES: |
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IMPLICIT NONE |
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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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|
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C !INPUT/OUTPUT PARAMETERS: |
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C == Routine arguments == |
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C skipCalcAngleC :: skip setting of grid-angle at cell-center location |
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C myThid :: my Thread Id Number |
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LOGICAL skipCalcAngleC |
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INTEGER myThid |
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CEOP |
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|
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C !LOCAL VARIABLES: |
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C == Local variables == |
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C bi,bj :: Tile indices |
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C i, j :: Loop counters |
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INTEGER bi, bj |
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INTEGER i, j |
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C pseudo velocities |
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_RL uPseudo(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL vPseudo(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL uC, vC, uNorm, tmpVal |
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CEOP |
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|
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C- For each tile ... |
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DO bj = myByLo(myThid), myByHi(myThid) |
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DO bi = myBxLo(myThid), myBxHi(myThid) |
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|
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C- compute pseudo velocities from stream function psi = -yG*deg2rad, |
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C that is, zonal flow |
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DO j = 1-OLy,sNy+OLy-1 |
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DO i = 1-OLx,sNx+OLx |
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IF ( _dyG(i,j,bi,bj).GT.0. ) THEN |
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uPseudo(i,j) = |
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& - ( yG(i,j,bi,bj) - yG(i,j+1,bi,bj) )*deg2rad |
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& / _dyG(i,j,bi,bj) |
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ELSE |
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uPseudo(i,j) = 0. |
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ENDIF |
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u2zonDir(i,j,bi,bj) = rSphere*uPseudo(i,j) |
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ENDDO |
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ENDDO |
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DO j = 1-OLy,sNy+OLy |
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DO i = 1-OLx,sNx+OLx-1 |
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IF ( _dxG(i,j,bi,bj).GT.0. ) THEN |
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vPseudo(i,j) = |
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& + ( yG(i,j,bi,bj) - yG(i+1,j,bi,bj) )*deg2rad |
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& / _dxG(i,j,bi,bj) |
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ELSE |
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vPseudo(i,j) = 0. |
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ENDIF |
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v2zonDir(i,j,bi,bj) = rSphere*vPseudo(i,j) |
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ENDDO |
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ENDDO |
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IF ( .NOT.skipCalcAngleC ) THEN |
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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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uC = 0.5*(uPseudo(i,j) + uPseudo(i+1,j)) |
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vC = 0.5*(vPseudo(i,j) + vPseudo(i,j+1)) |
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uNorm = SQRT(uC*uC+vC*vC) |
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IF ( uNorm .NE. 0. _d 0 ) uNorm = 1. _d 0/uNorm |
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angleCosC(i,j,bi,bj) = uC*uNorm |
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angleSinC(i,j,bi,bj) = -vC*uNorm |
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ENDDO |
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ENDDO |
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ENDIF |
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|
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C- To check angular momentum conservation, use an alternative definition |
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C of grid-angles cosine (@ U pt) & sine (@ V pt) (consistent with |
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C stream-function of solid-body velocity field). |
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DO j = 1-OLy,sNy+OLy-1 |
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DO i = 1-OLx,sNx+OLx |
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C- Note: most natural way would be to divide by dyG (as below); but scaling by |
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C dxC/rAw ensures that u2zonDir is exactly =1 with current Lat-Lon grid |
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c tmpVal = _dyG(i,j,bi,bj) * COS( deg2rad* |
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tmpVal = _rAw(i,j,bi,bj) * COS( deg2rad* |
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& ( yG(i,j,bi,bj) + yG(i,j+1,bi,bj) )*halfRL ) |
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IF ( tmpVal.GT.0. ) THEN |
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u2zonDir(i,j,bi,bj) = rSphere |
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& *( SIN( yG(i,j+1,bi,bj)*deg2rad ) |
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& - SIN( yG(i, j, bi,bj)*deg2rad ) |
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& )* _dxC(i,j,bi,bj)/tmpVal |
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c & )/tmpVal |
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ELSE |
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u2zonDir(i,j,bi,bj) = 1. |
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ENDIF |
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ENDDO |
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ENDDO |
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DO j = 1-OLy,sNy+OLy |
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DO i = 1-OLx,sNx+OLx-1 |
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C- Note: most natural way would be to divide by dxG (as below); for symetry |
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C reason with u2zonDir expression, we use instead dyC/rAs scaling factor |
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c tmpVal = _dxG(i,j,bi,bj) * COS( deg2rad* |
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tmpVal = _rAs(i,j,bi,bj) * COS( deg2rad* |
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& ( yG(i,j,bi,bj) + yG(i+1,j,bi,bj) )*halfRL ) |
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IF ( tmpVal.GT.0. ) THEN |
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v2zonDir(i,j,bi,bj) = -rSphere |
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& *( SIN( yG(i+1,j,bi,bj)*deg2rad ) |
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& - SIN( yG(i,j,bi,bj)*deg2rad ) |
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& )* _dyC(i,j,bi,bj)/tmpVal |
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c & )/tmpVal |
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ELSE |
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v2zonDir(i,j,bi,bj) = 0. |
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ENDIF |
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ENDDO |
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ENDDO |
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|
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C- bi,bj-loops |
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ENDDO |
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ENDDO |
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|
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RETURN |
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END |
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