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C $Header: /u/gcmpack/MITgcm/pkg/shelfice/shelfice_u_drag.F,v 1.12 2015/02/14 21:58:05 jmc Exp $ |
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C $Name: $ |
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|
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#include "SHELFICE_OPTIONS.h" |
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|
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CBOP |
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C !ROUTINE: SHELFICE_U_DRAG |
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|
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C !INTERFACE: ========================================================== |
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SUBROUTINE SHELFICE_U_DRAG( |
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I bi, bj, k, |
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I uFld, vFld, KE, kappaRU, |
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O uDragTerms, |
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I myThid ) |
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|
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C !DESCRIPTION: |
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C Calculates the drag due to friction and the no-slip condition at the |
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C bottom of the shelf-ice (in analogy to bottom drag) |
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C \begin{equation*} |
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C G^u_{drag} = - ( r_b + C_D |v| + \frac{2}{\Delta r_c} ) u |
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C \end{equation*} |
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|
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C !USES: =============================================================== |
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IMPLICIT NONE |
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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 "SHELFICE.h" |
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|
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C !INPUT PARAMETERS: =================================================== |
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C bi,bj :: tile indices |
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C k :: vertical level |
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C uFld :: zonal flow |
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C vFld :: meridional flow |
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C KE :: Kinetic energy |
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C kappaRU :: vertical viscosity |
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C myThid :: thread number |
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INTEGER bi,bj,k |
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_RL uFld(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL vFld(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL KE(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL kappaRU(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr+1) |
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INTEGER myThid |
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|
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C !OUTPUT PARAMETERS: ================================================== |
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C uDragTerms :: drag term |
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_RL uDragTerms(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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|
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#ifdef ALLOW_SHELFICE |
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C !LOCAL VARIABLES : ==================================================== |
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C i,j :: loop indices |
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C Kp1 :: =k+1 for k<Nr, =Nr for k>=Nr |
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INTEGER i,j,kUpC,kTop |
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_RL viscFac, uSq |
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_RL rdrckp1 |
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CEOP |
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|
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C- No-slip BCs impose a drag at top |
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IF ( usingZCoords ) THEN |
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kTop = 1 |
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kUpC = k |
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ELSE |
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kTop = Nr |
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kUpC = k+1 |
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ENDIF |
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rdrckp1=recip_drC(kUpC) |
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CML IF (k.EQ.kTop) rdrckp1=recip_drF(k) |
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viscFac=0. |
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IF (no_slip_shelfice) viscFac=2. |
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|
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C-- Friction at the bottom of ice-shelf (no-slip BC) |
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IF ( no_slip_shelfice ) THEN |
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C- ignores partial-cell reduction of the distance to the surface |
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DO j=1-OLy,sNy+OLy-1 |
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DO i=1-OLx+1,sNx+OLx-1 |
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IF ( k.EQ.MAX( kTopC(i-1,j,bi,bj),kTopC(i,j,bi,bj) ) ) THEN |
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uDragTerms(i,j) = |
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& - _recip_hFacW(i,j,k,bi,bj)*recip_drF(k) |
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& * kappaRU(i,j,kUpC)*rdrckp1*viscFac |
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#ifndef IMPLICIT_BOTTOMSIDEDRAG |
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& * uFld(i,j) |
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#endif |
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ELSE |
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uDragTerms(i,j) = 0. _d 0 |
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ENDIF |
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ENDDO |
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ENDDO |
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ELSE |
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DO j=1-OLy,sNy+OLy |
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DO i=1-OLx,sNx+OLx |
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uDragTerms(i,j) = 0. _d 0 |
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ENDDO |
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ENDDO |
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ENDIF |
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IF ( no_slip_shelfice .AND. bottomVisc_pCell ) THEN |
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C- friction accounts for true distance (including hFac) to the surface |
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DO j=1-OLy,sNy+OLy-1 |
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DO i=1-OLx+1,sNx+OLx-1 |
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uDragTerms(i,j) = uDragTerms(i,j) |
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& * _recip_hFacW(i,j,k,bi,bj) |
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ENDDO |
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ENDDO |
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ENDIF |
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|
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C-- Add Linear drag: |
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IF ( SHELFICEDragLinear.NE.zeroRL ) THEN |
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DO j=1-OLy,sNy+OLy-1 |
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DO i=1-OLx+1,sNx+OLx-1 |
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IF ( k.EQ.MAX( kTopC(i-1,j,bi,bj),kTopC(i,j,bi,bj) ) ) THEN |
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uDragTerms(i,j) = uDragTerms(i,j) |
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& - _recip_hFacW(i,j,k,bi,bj)*recip_drF(k) |
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& * SHELFICEDragLinear |
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#ifndef IMPLICIT_BOTTOMSIDEDRAG |
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& * uFld(i,j) |
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#endif |
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ENDIF |
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ENDDO |
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ENDDO |
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ENDIF |
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|
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C-- Add quadratic drag |
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IF ( SHELFICEselectDragQuadr.EQ.0 ) THEN |
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C- average grid-cell-center KE to get velocity norm @ U.pt |
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DO j=1-OLy,sNy+OLy-1 |
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DO i=1-OLx+1,sNx+OLx-1 |
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uSq = 0. _d 0 |
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IF ( k.EQ.MAX( kTopC(i-1,j,bi,bj),kTopC(i,j,bi,bj) ) ) THEN |
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uSq = KE(i,j)+KE(i-1,j) |
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ENDIF |
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IF ( uSq.GT.zeroRL ) THEN |
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uDragTerms(i,j) = uDragTerms(i,j) |
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& - _recip_hFacW(i,j,k,bi,bj)*recip_drF(k) |
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& * SHELFICEDragQuadratic*SQRT(uSq) |
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#ifndef IMPLICIT_BOTTOMSIDEDRAG |
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& * uFld(i,j) |
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#endif |
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ENDIF |
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ENDDO |
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ENDDO |
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ELSEIF ( SHELFICEselectDragQuadr.EQ.1 ) THEN |
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C- calculate locally velocity norm @ U.pt (local U & 4 V averaged) |
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DO j=1-OLy,sNy+OLy-1 |
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DO i=1-OLx+1,sNx+OLx-1 |
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uSq = 0. _d 0 |
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IF ( k.EQ.MAX( kTopC(i-1,j,bi,bj),kTopC(i,j,bi,bj) ) ) THEN |
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uSq = uFld(i,j)*uFld(i,j) |
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& + ( (vFld(i-1, j )*vFld(i-1, j )*hFacS(i-1, j ,k,bi,bj) |
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& +vFld( i , j )*vFld( i , j )*hFacS( i , j ,k,bi,bj)) |
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& + (vFld(i-1,j+1)*vFld(i-1,j+1)*hFacS(i-1,j+1,k,bi,bj) |
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& +vFld( i ,j+1)*vFld( i ,j+1)*hFacS( i ,j+1,k,bi,bj)) |
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& )*recip_hFacW(i,j,k,bi,bj)*0.25 _d 0 |
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ENDIF |
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IF ( uSq.GT.zeroRL ) THEN |
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uDragTerms(i,j) = uDragTerms(i,j) |
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& - _recip_hFacW(i,j,k,bi,bj)*recip_drF(k) |
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& * SHELFICEDragQuadratic*SQRT(uSq) |
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#ifndef IMPLICIT_BOTTOMSIDEDRAG |
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& * uFld(i,j) |
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#endif |
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ENDIF |
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ENDDO |
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ENDDO |
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ELSEIF ( SHELFICEselectDragQuadr.EQ.2 ) THEN |
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C- same as above but using wet-point method to average 4 V |
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DO j=1-OLy,sNy+OLy-1 |
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DO i=1-OLx+1,sNx+OLx-1 |
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uSq = 0. _d 0 |
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IF ( k.EQ.MAX( kTopC(i-1,j,bi,bj),kTopC(i,j,bi,bj) ) ) THEN |
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uSq = ( hFacS(i-1, j ,k,bi,bj) + hFacS( i , j ,k,bi,bj) ) |
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& + ( hFacS(i-1,j+1,k,bi,bj) + hFacS( i ,j+1,k,bi,bj) ) |
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IF ( uSq.GT.zeroRL ) THEN |
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uSq = uFld(i,j)*uFld(i,j) |
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& +( (vFld(i-1, j )*vFld(i-1, j )*hFacS(i-1, j ,k,bi,bj) |
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& +vFld( i , j )*vFld( i , j )*hFacS( i , j ,k,bi,bj)) |
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& + (vFld(i-1,j+1)*vFld(i-1,j+1)*hFacS(i-1,j+1,k,bi,bj) |
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& +vFld( i ,j+1)*vFld( i ,j+1)*hFacS( i ,j+1,k,bi,bj)) |
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& )/uSq |
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ELSE |
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uSq = uFld(i,j)*uFld(i,j) |
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ENDIF |
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ENDIF |
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IF ( uSq.GT.zeroRL ) THEN |
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uDragTerms(i,j) = uDragTerms(i,j) |
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& - _recip_hFacW(i,j,k,bi,bj)*recip_drF(k) |
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& * SHELFICEDragQuadratic*SQRT(uSq) |
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#ifndef IMPLICIT_BOTTOMSIDEDRAG |
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& * uFld(i,j) |
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#endif |
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ENDIF |
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ENDDO |
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ENDDO |
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ENDIF |
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|
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#ifdef IMPLICIT_BOTTOMSIDEDRAG |
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DO j=1-OLy+1,sNy+OLy-1 |
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DO i=1-OLx,sNx+OLx-1 |
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uDragTerms(i,j) = uDragTerms(i,j)*uFld(i,j) / |
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& (1. - deltaTmom*uDragTerms(i,j)) |
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ENDDO |
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ENDDO |
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#endif |
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|
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#ifdef ALLOW_DIAGNOSTICS |
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IF ( useDiagnostics .AND. |
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& ( no_slip_shelfice .OR. SHELFICEDragLinear.NE.zeroRL |
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& .OR. SHELFICEselectDragQuadr.GE.0 ) |
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& ) THEN |
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CALL DIAGNOSTICS_FILL(uDragTerms,'SHIUDrag',k,1,2,bi,bj,myThid) |
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ENDIF |
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#endif /* ALLOW_DIAGNOSTICS */ |
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#endif /* ALLOW_SHELFICE */ |
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|
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RETURN |
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END |
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