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C $Header: /u/gcmpack/MITgcm/pkg/mom_common/mom_v_bottomdrag.F,v 1.16 2015/01/04 00:00:36 jmc Exp $ |
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C $Name: $ |
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|
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#include "MOM_COMMON_OPTIONS.h" |
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#ifdef ALLOW_CTRL |
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# include "CTRL_OPTIONS.h" |
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#endif |
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|
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CBOP |
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C !ROUTINE: MOM_V_BOTTOMDRAG |
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|
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C !INTERFACE: ========================================================== |
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SUBROUTINE MOM_V_BOTTOMDRAG( |
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I bi, bj, k, |
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I uFld, vFld, KE, kappaRV, |
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O vDragTerms, |
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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 bottom: |
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C \begin{equation*} |
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C G^v_{drag} = - \frac{1}{\Delta r_f} ( r_b + C_D |v| + \frac{2}{\Delta r_c} ) v |
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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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#ifdef ALLOW_CTRL |
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# include "CTRL_FIELDS.h" |
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#endif |
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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 kappaRV :: 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 kappaRV(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 vDragTerms :: drag term |
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_RL vDragTerms(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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|
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C !LOCAL VARIABLES: ==================================================== |
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C i,j :: loop indices |
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INTEGER i,j,kDown,kLowF,kBottom |
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_RL viscFac, dragFac, vSq |
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_RL recDrC |
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_RL recDrF_bot(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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CEOP |
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|
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C- No-slip BCs impose a drag at bottom |
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viscFac = 0. |
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IF (no_slip_bottom) viscFac = 2. |
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IF ( usingZCoords ) THEN |
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kBottom = Nr |
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kDown = MIN(k+1,Nr) |
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kLowF = k+1 |
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c dragFac = mass2rUnit*rhoConst |
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c dragFac = wUnit2rVel(k+1) |
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dragFac = 1. _d 0 |
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ELSE |
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kBottom = 1 |
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kDown = MAX(k-1,1) |
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kLowF = k |
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dragFac = mass2rUnit*rhoConst |
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c dragFac = wUnit2rVel(k) |
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ENDIF |
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IF ( k.EQ.kBottom ) THEN |
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recDrC = recip_drF(k) |
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DO j=1-OLy,sNy+OLy |
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DO i=1-OLx,sNx+OLx |
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recDrF_bot(i,j) = _recip_hFacS(i,j,k,bi,bj)*recip_drF(k) |
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ENDDO |
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ENDDO |
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ELSE |
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recDrC = recip_drC(kLowF) |
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DO j=1-OLy,sNy+OLy |
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DO i=1-OLx,sNx+OLx |
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recDrF_bot(i,j) = _recip_hFacS(i,j,k,bi,bj)*recip_drF(k) |
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& * ( 1. _d 0 -_maskS(i,j,kDown,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-- Linear bottom drag: |
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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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vDragTerms(i,j) = |
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& - recDrF_bot(i,j) |
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& *( bottomDragLinear*dragFac |
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#ifdef ALLOW_BOTTOMDRAG_CONTROL |
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& + halfRL*( bottomDragFld(i,j-1,bi,bj) |
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& + bottomDragFld(i,j,bi,bj) )*dragFac |
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#endif |
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& )*vFld(i,j) |
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ENDDO |
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ENDDO |
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|
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C-- Add friction at the bottom (no-slip BC) |
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IF ( no_slip_bottom .AND. bottomVisc_pCell ) THEN |
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C- bottom friction accounts for true distance (including hFac) to the bottom |
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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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vDragTerms(i,j) = vDragTerms(i,j) |
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& - recDrF_bot(i,j) |
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& *( kappaRV(i,j,kLowF)*recDrC*viscFac |
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& *_recip_hFacS(i,j,k,bi,bj) |
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& )*vFld(i,j) |
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ENDDO |
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ENDDO |
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ELSEIF ( no_slip_bottom ) THEN |
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C- ignore partial-cell reduction of the distance to the bottom |
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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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vDragTerms(i,j) = vDragTerms(i,j) |
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& - recDrF_bot(i,j) |
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& *( kappaRV(i,j,kLowF)*recDrC*viscFac |
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& )*vFld(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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C-- Add quadratic bottom drag |
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IF ( selectBotDragQuadr.EQ.0 ) THEN |
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C- average grid-cell-center KE to get velocity norm @ V.pt |
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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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IF ( (KE(i,j)+KE(i,j-1)) .GT. 0. ) THEN |
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vDragTerms(i,j) = vDragTerms(i,j) |
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& - recDrF_bot(i,j) |
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& *bottomDragQuadratic*SQRT(KE(i,j)+KE(i,j-1))*dragFac |
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& *vFld(i,j) |
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ENDIF |
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ENDDO |
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ENDDO |
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ELSEIF ( selectBotDragQuadr.EQ.1 ) THEN |
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C- calculate locally velocity norm @ V.pt (local V & 4 U averaged) |
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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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vSq = vFld(i,j)*vFld(i,j) |
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& + ( (uFld( i ,j-1)*uFld( i ,j-1)*hFacW( i ,j-1,k,bi,bj) |
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& +uFld( i , j )*uFld( i , j )*hFacW( i , j ,k,bi,bj)) |
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& + (uFld(i+1,j-1)*uFld(i+1,j-1)*hFacW(i+1,j-1,k,bi,bj) |
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& +uFld(i+1, j )*uFld(i+1, j )*hFacW(i+1, j ,k,bi,bj)) |
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& )*recip_hFacS(i,j,k,bi,bj)*0.25 _d 0 |
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IF ( vSq.GT.zeroRL ) THEN |
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vDragTerms(i,j) = vDragTerms(i,j) |
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& - recDrF_bot(i,j) |
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& *bottomDragQuadratic*SQRT(vSq)*dragFac |
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& *vFld(i,j) |
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ENDIF |
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ENDDO |
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ENDDO |
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ELSEIF ( selectBotDragQuadr.EQ.2 ) THEN |
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C- same as above but using wet-point method to average 4 U |
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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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vSq = ( hFacW( i ,j-1,k,bi,bj) + hFacW( i , j ,k,bi,bj) ) |
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& + ( hFacW(i+1,j-1,k,bi,bj) + hFacW(i+1, j ,k,bi,bj) ) |
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IF ( vSq.GT.zeroRL ) THEN |
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vSq = vFld(i,j)*vFld(i,j) |
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& +( (uFld( i ,j-1)*uFld( i ,j-1)*hFacW( i ,j-1,k,bi,bj) |
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& +uFld( i , j )*uFld( i , j )*hFacW( i , j ,k,bi,bj)) |
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& + (uFld(i+1,j-1)*uFld(i+1,j-1)*hFacW(i+1,j-1,k,bi,bj) |
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& +uFld(i+1, j )*uFld(i+1, j )*hFacW(i+1, j ,k,bi,bj)) |
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& )/vSq |
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ELSE |
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vSq = vFld(i,j)*vFld(i,j) |
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ENDIF |
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IF ( vSq.GT.zeroRL ) THEN |
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vDragTerms(i,j) = vDragTerms(i,j) |
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& - recDrF_bot(i,j) |
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& *bottomDragQuadratic*SQRT(vSq)*dragFac |
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& *vFld(i,j) |
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ENDIF |
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ENDDO |
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ENDDO |
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ELSEIF ( selectBotDragQuadr.NE.-1 ) THEN |
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STOP 'MOM_V_BOTTOMDRAG: invalid selectBotDragQuadr value' |
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ENDIF |
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|
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#ifdef ALLOW_DIAGNOSTICS |
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IF (useDiagnostics) THEN |
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CALL DIAGNOSTICS_FILL(vDragTerms,'VBotDrag',k,1,2,bi,bj,myThid) |
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ENDIF |
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#endif /* ALLOW_DIAGNOSTICS */ |
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|
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RETURN |
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END |
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