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mom_calc_strain.F
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mom_calc_strain.F
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C $Header: /u/gcmpack/MITgcm/pkg/mom_common/mom_calc_strain.F,v 1.5 2015/09/10 17:53:04 jmc Exp $
C $Name: $
#include "MOM_COMMON_OPTIONS.h"
CBOP
C !ROUTINE: MOM_CALC_STRAIN
C !INTERFACE: ==========================================================
SUBROUTINE MOM_CALC_STRAIN(
I bi,bj,k,
I uFld, vFld, hFacZ,
O strain,
I myThid )
C !DESCRIPTION:
C Calculates the strain of the horizontal flow field (at vorticity points):
C \begin{equation*}
C D_S = \frac{\Delta y_u}{\Delta x_v} \delta_i \frac{v}{\Delta y_c}
C + \frac{\Delta x_v}{\Delta y_u} \delta_j \frac{u}{\Delta x_c}
C \end{equation*}
C assuming free-slip boundaries.
C !USES: ===============================================================
IMPLICIT NONE
#include "SIZE.h"
#include "EEPARAMS.h"
#include "PARAMS.h"
#include "GRID.h"
C !INPUT PARAMETERS: ===================================================
C bi,bj :: tile indices
C k :: vertical level
C uFld :: zonal flow
C vFld :: meridional flow
C hFacZ :: open-water thickness at vorticity points
C myThid :: thread number
INTEGER bi,bj,k
_RL uFld(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
_RL vFld(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
_RS hFacZ(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
INTEGER myThid
C !OUTPUT PARAMETERS: ==================================================
C strain :: strain of horizontal flow
_RL strain(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
C !LOCAL VARIABLES: ====================================================
C i,j :: loop indices
INTEGER i,j
CEOP
DO j=2-OLy,sNy+OLy
DO i=2-OLx,sNx+OLx
C Strain of horizontal flow field (ignoring lopping factors)
strain(i,j)=
& ( dyC( i , j ,bi,bj)*vFld( i , j )
& -dyC(i-1, j ,bi,bj)*vFld(i-1, j )
& +dxC( i , j ,bi,bj)*uFld( i , j )
& -dxC( i ,j-1,bi,bj)*uFld( i ,j-1)
& )*recip_rAz(i,j,bi,bj)*recip_deepFacC(k)
c strain(i,j)=
c & dyU(i,j,bi,bj)*recip_dxV(i,j,bi,bj)*(
c & vFld( i , j )*recip_dyC( i , j ,bi,bj)
c & -vFld(i-1, j )*recip_dyC(i-1, j ,bi,bj) )
c & +dxV(i,j,bi,bj)*recip_dyU(i,j,bi,bj)*(
c & +uFld( i , j )*recip_dxC( i , j ,bi,bj)
c & -uFld( i ,j-1)*recip_dxC( i ,j-1,bi,bj) )
C Set strain to zero on boundaries (free-slip)
C mask is now applied afterwards, outside this S/R.
c IF (hFacZ(i,j).EQ.0.) THEN
c strain(i,j)=0.
c ENDIF
ENDDO
ENDDO
C Special stuff for Cubed Sphere
IF (useCubedSphereExchange) THEN
c STOP 'S/R MOM_CALC_STRAIN: We should not use strain on the cube!'
ENDIF
RETURN
END