C $Header: /u/gcmpack/MITgcm/model/src/apply_forcing.F,v 1.8 2016/02/14 00:08:49 jmc Exp $
C $Name:  $

#include "PACKAGES_CONFIG.h"
#include "CPP_OPTIONS.h"

C--  File apply_forcing.F:
C--   Contents
C--   o APPLY_FORCING_U
C--   o APPLY_FORCING_V
C--   o APPLY_FORCING_T
C--   o APPLY_FORCING_S

C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
CBOP
C     !ROUTINE: APPLY_FORCING_U
C     !INTERFACE:
      SUBROUTINE APPLY_FORCING_U(
     U                     gU_arr,
     I                     iMin,iMax,jMin,jMax, k, bi, bj,
     I                     myTime, myIter, myThid )
C     !DESCRIPTION: \bv
C     *==========================================================*
C     | S/R APPLY_FORCING_U
C     | o Contains problem specific forcing for zonal velocity.
C     *==========================================================*
C     | Adds terms to gU for forcing by external sources
C     | e.g. wind stress, bottom friction etc ...
C     *==========================================================*
C     \ev

C     !USES:
      IMPLICIT NONE
C     == Global data ==
#include "SIZE.h"
#include "EEPARAMS.h"
#include "PARAMS.h"
#include "GRID.h"
#include "DYNVARS.h"
#include "FFIELDS.h"

C     !INPUT/OUTPUT PARAMETERS:
C     gU_arr    :: the tendency array
C     iMin,iMax :: Working range of x-index for applying forcing.
C     jMin,jMax :: Working range of y-index for applying forcing.
C     k         :: Current vertical level index
C     bi,bj     :: Current tile indices
C     myTime    :: Current time in simulation
C     myIter    :: Current iteration number
C     myThid    :: my Thread Id number
      _RL     gU_arr(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      INTEGER iMin, iMax, jMin, jMax
      INTEGER k, bi, bj
      _RL     myTime
      INTEGER myIter
      INTEGER myThid

C     !LOCAL VARIABLES:
C     i,j       :: Loop counters
C     kSurface  :: index of surface level
      INTEGER i, j
#ifdef USE_OLD_EXTERNAL_FORCING
      _RL     locVar(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      _RL     tmpVar(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
#else
      INTEGER kSurface
#endif /* USE_OLD_EXTERNAL_FORCING */
CEOP

#ifdef USE_OLD_EXTERNAL_FORCING

      DO j=1-OLy,sNy+OLy
        DO i=1-OLx,sNx+OLx
          locVar(i,j) = gU(i,j,k,bi,bj)
        ENDDO
      ENDDO
      CALL EXTERNAL_FORCING_U(
     I              iMin, iMax, jMin, jMax, bi, bj, k,
     I              myTime, myThid )
C-    Use 2-d local array tmpVar and split loop in 2 parts to avoid compiler
C     to mess-up this part by re-arranging the order of instructions (wrong
C     when gU and gU_arr are the same array, i.e., called with argument gU).
      DO j=1-OLy,sNy+OLy
        DO i=1-OLx,sNx+OLx
          tmpVar(i,j) = gU(i,j,k,bi,bj) - locVar(i,j)
          gU(i,j,k,bi,bj) = locVar(i,j)
        ENDDO
      ENDDO
C-    not needed since APPLY_FORCING_U is no longer called with argument gU
c     CALL FOOL_THE_COMPILER_RL( tmpVar(1,1) )
      DO j=1-OLy,sNy+OLy
        DO i=1-OLx,sNx+OLx
          gU_arr(i,j) = gU_arr(i,j) + tmpVar(i,j)
        ENDDO
      ENDDO

#else  /* USE_OLD_EXTERNAL_FORCING */

      IF ( fluidIsAir ) THEN
       kSurface = 0
      ELSEIF ( usingPCoords ) THEN
       kSurface = Nr
      ELSE
       kSurface = 1
      ENDIF

C--   Forcing term
#ifdef ALLOW_AIM
      IF ( useAIM ) CALL AIM_TENDENCY_APPLY_U(
     U                       gU_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_AIM */

#ifdef ALLOW_ATM_PHYS
      IF ( useAtm_Phys ) CALL ATM_PHYS_TENDENCY_APPLY_U(
     U                       gU_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_ATM_PHYS */

#ifdef ALLOW_FIZHI
      IF ( useFIZHI ) CALL FIZHI_TENDENCY_APPLY_U(
     U                       gU_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_FIZHI */

C     Ocean: Add momentum surface forcing (e.g., wind-stress) in surface level
      IF ( k .EQ. kSurface ) THEN
c      DO j=1,sNy
C-jmc: Without CD-scheme, this is OK ; but with CD-scheme, needs to cover [0:sNy+1]
       DO j=0,sNy+1
        DO i=1,sNx+1
          gU_arr(i,j) = gU_arr(i,j)
     &      +foFacMom*surfaceForcingU(i,j,bi,bj)
     &      *recip_drF(k)*_recip_hFacW(i,j,k,bi,bj)
        ENDDO
       ENDDO
      ELSEIF ( kSurface.EQ.-1 ) THEN
       DO j=0,sNy+1
        DO i=1,sNx+1
         IF ( kSurfW(i,j,bi,bj).EQ.k ) THEN
          gU_arr(i,j) = gU_arr(i,j)
     &      +foFacMom*surfaceForcingU(i,j,bi,bj)
     &      *recip_drF(k)*_recip_hFacW(i,j,k,bi,bj)
         ENDIF
        ENDDO
       ENDDO
      ENDIF

#ifdef ALLOW_EDDYPSI
         CALL TAUEDDY_TENDENCY_APPLY_U(
     U                 gU_arr,
     I                 iMin,iMax,jMin,jMax, k, bi,bj,
     I                 myTime, myIter, myThid )
#endif

#ifdef ALLOW_RBCS
      IF (useRBCS) THEN
        CALL RBCS_ADD_TENDENCY(
     U                 gU_arr,
     I                 k, bi, bj, -1,
     I                 myTime, myIter, myThid )

      ENDIF
#endif /* ALLOW_RBCS */

#ifdef ALLOW_OBCS
      IF (useOBCS) THEN
        CALL OBCS_SPONGE_U(
     U                   gU_arr,
     I                   iMin,iMax,jMin,jMax, k, bi,bj,
     I                   myTime, myIter, myThid )
      ENDIF
#endif /* ALLOW_OBCS */

#ifdef ALLOW_MYPACKAGE
      IF ( useMYPACKAGE ) THEN
        CALL MYPACKAGE_TENDENCY_APPLY_U(
     U                 gU_arr,
     I                 iMin,iMax,jMin,jMax, k, bi,bj,
     I                 myTime, myIter, myThid )
      ENDIF
#endif /* ALLOW_MYPACKAGE */

#endif /* USE_OLD_EXTERNAL_FORCING */

      RETURN
      END

C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
CBOP
C     !ROUTINE: APPLY_FORCING_V
C     !INTERFACE:
      SUBROUTINE APPLY_FORCING_V(
     U                     gV_arr,
     I                     iMin,iMax,jMin,jMax, k, bi, bj,
     I                     myTime, myIter, myThid )
C     !DESCRIPTION: \bv
C     *==========================================================*
C     | S/R APPLY_FORCING_V
C     | o Contains problem specific forcing for merid velocity.
C     *==========================================================*
C     | Adds terms to gV for forcing by external sources
C     | e.g. wind stress, bottom friction etc ...
C     *==========================================================*
C     \ev

C     !USES:
      IMPLICIT NONE
C     == Global data ==
#include "SIZE.h"
#include "EEPARAMS.h"
#include "PARAMS.h"
#include "GRID.h"
#include "DYNVARS.h"
#include "FFIELDS.h"

C     !INPUT/OUTPUT PARAMETERS:
C     gV_arr    :: the tendency array
C     iMin,iMax :: Working range of x-index for applying forcing.
C     jMin,jMax :: Working range of y-index for applying forcing.
C     k         :: Current vertical level index
C     bi,bj     :: Current tile indices
C     myTime    :: Current time in simulation
C     myIter    :: Current iteration number
C     myThid    :: my Thread Id number
      _RL     gV_arr(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      INTEGER iMin, iMax, jMin, jMax
      INTEGER k, bi, bj
      _RL     myTime
      INTEGER myIter
      INTEGER myThid

C     !LOCAL VARIABLES:
C     i,j       :: Loop counters
C     kSurface  :: index of surface level
      INTEGER i, j
#ifdef USE_OLD_EXTERNAL_FORCING
      _RL     locVar(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      _RL     tmpVar(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
#else
      INTEGER kSurface
#endif /* USE_OLD_EXTERNAL_FORCING */
CEOP

#ifdef USE_OLD_EXTERNAL_FORCING

      DO j=1-OLy,sNy+OLy
        DO i=1-OLx,sNx+OLx
          locVar(i,j) = gV(i,j,k,bi,bj)
        ENDDO
      ENDDO
      CALL EXTERNAL_FORCING_V(
     I              iMin, iMax, jMin, jMax, bi, bj, k,
     I              myTime, myThid )
C-    Use 2-d local array tmpVar and split loop in 2 parts to avoid compiler
C     to mess-up this part by re-arranging the order of instructions (wrong
C     when gV and gV_arr are the same array, i.e., called with argument gV).
      DO j=1-OLy,sNy+OLy
        DO i=1-OLx,sNx+OLx
          tmpVar(i,j) = gV(i,j,k,bi,bj) - locVar(i,j)
          gV(i,j,k,bi,bj) = locVar(i,j)
        ENDDO
      ENDDO
C-    not needed since APPLY_FORCING_V is no longer called with argument gV
c     CALL FOOL_THE_COMPILER_RL( tmpVar(1,1) )
      DO j=1-OLy,sNy+OLy
        DO i=1-OLx,sNx+OLx
          gV_arr(i,j) = gV_arr(i,j) + tmpVar(i,j)
        ENDDO
      ENDDO

#else  /* USE_OLD_EXTERNAL_FORCING */

      IF ( fluidIsAir ) THEN
       kSurface = 0
      ELSEIF ( usingPCoords ) THEN
       kSurface = Nr
      ELSE
       kSurface = 1
      ENDIF

C--   Forcing term
#ifdef ALLOW_AIM
      IF ( useAIM ) CALL AIM_TENDENCY_APPLY_V(
     U                       gV_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_AIM */

#ifdef ALLOW_ATM_PHYS
      IF ( useAtm_Phys ) CALL ATM_PHYS_TENDENCY_APPLY_V(
     U                       gV_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_ATM_PHYS */

#ifdef ALLOW_FIZHI
      IF ( useFIZHI ) CALL FIZHI_TENDENCY_APPLY_V(
     U                       gV_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_FIZHI */

C     Ocean: Add momentum surface forcing (e.g., wind-stress) in surface level
      IF ( k .EQ. kSurface ) THEN
       DO j=1,sNy+1
c       DO i=1,sNx
C-jmc: Without CD-scheme, this is OK ; but with CD-scheme, needs to cover [0:sNx+1]
        DO i=0,sNx+1
          gV_arr(i,j) = gV_arr(i,j)
     &      +foFacMom*surfaceForcingV(i,j,bi,bj)
     &      *recip_drF(k)*_recip_hFacS(i,j,k,bi,bj)
        ENDDO
       ENDDO
      ELSEIF ( kSurface.EQ.-1 ) THEN
       DO j=1,sNy+1
        DO i=0,sNx+1
         IF ( kSurfS(i,j,bi,bj).EQ.k ) THEN
          gV_arr(i,j) = gV_arr(i,j)
     &      +foFacMom*surfaceForcingV(i,j,bi,bj)
     &      *recip_drF(k)*_recip_hFacS(i,j,k,bi,bj)
         ENDIF
        ENDDO
       ENDDO
      ENDIF

#ifdef ALLOW_EDDYPSI
         CALL TAUEDDY_TENDENCY_APPLY_V(
     U                 gV_arr,
     I                 iMin,iMax,jMin,jMax, k, bi,bj,
     I                 myTime, myIter, myThid )
#endif

#ifdef ALLOW_RBCS
      IF (useRBCS) THEN
        CALL RBCS_ADD_TENDENCY(
     U                 gV_arr,
     I                 k, bi, bj, -2,
     I                 myTime, myIter, myThid )
      ENDIF
#endif /* ALLOW_RBCS */

#ifdef ALLOW_OBCS
      IF (useOBCS) THEN
        CALL OBCS_SPONGE_V(
     U                   gV_arr,
     I                   iMin,iMax,jMin,jMax, k, bi,bj,
     I                   myTime, myIter, myThid )
      ENDIF
#endif /* ALLOW_OBCS */

#ifdef ALLOW_MYPACKAGE
      IF ( useMYPACKAGE ) THEN
        CALL MYPACKAGE_TENDENCY_APPLY_V(
     U                 gV_arr,
     I                 iMin,iMax,jMin,jMax, k, bi,bj,
     I                 myTime, myIter, myThid )
      ENDIF
#endif /* ALLOW_MYPACKAGE */

#endif /* USE_OLD_EXTERNAL_FORCING */

      RETURN
      END

C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
CBOP
C     !ROUTINE: APPLY_FORCING_T
C     !INTERFACE:
      SUBROUTINE APPLY_FORCING_T(
     U                     gT_arr,
     I                     iMin,iMax,jMin,jMax, k, bi, bj,
     I                     myTime, myIter, myThid )
C     !DESCRIPTION: \bv
C     *==========================================================*
C     | S/R APPLY_FORCING_T
C     | o Contains problem specific forcing for temperature.
C     *==========================================================*
C     | Adds terms to gT for forcing by external sources
C     | e.g. heat flux, climatalogical relaxation, etc ...
C     *==========================================================*
C     \ev

C     !USES:
      IMPLICIT NONE
C     == Global data ==
#include "SIZE.h"
#include "EEPARAMS.h"
#include "PARAMS.h"
#include "GRID.h"
#include "DYNVARS.h"
#include "FFIELDS.h"
#include "SURFACE.h"

C     !INPUT/OUTPUT PARAMETERS:
C     gT_arr    :: the tendency array
C     iMin,iMax :: Working range of x-index for applying forcing.
C     jMin,jMax :: Working range of y-index for applying forcing.
C     k         :: Current vertical level index
C     bi,bj     :: Current tile indices
C     myTime    :: Current time in simulation
C     myIter    :: Current iteration number
C     myThid    :: my Thread Id number
      _RL     gT_arr(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      INTEGER iMin, iMax, jMin, jMax
      INTEGER k, bi, bj
      _RL     myTime
      INTEGER myIter
      INTEGER myThid

C     !LOCAL VARIABLES:
C     i,j       :: Loop counters
C     kSurface  :: index of surface level
      INTEGER i, j
#ifndef USE_OLD_EXTERNAL_FORCING
      INTEGER kSurface
      INTEGER km, kc, kp
      _RL     tmpVar(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      _RL tmpFac, delPI
      _RL recip_Cp
#ifdef SHORTWAVE_HEATING
      _RL minusone
      PARAMETER (minusOne=-1.)
      _RL swfracb(2)
      INTEGER kp1
#endif
#endif /* USE_OLD_EXTERNAL_FORCING */
CEOP

#ifdef USE_OLD_EXTERNAL_FORCING

      DO j=1-OLy,sNy+OLy
        DO i=1-OLx,sNx+OLx
          gT(i,j,k,bi,bj) = 0. _d 0
        ENDDO
      ENDDO
      CALL EXTERNAL_FORCING_T(
     I              iMin, iMax, jMin, jMax, bi, bj, k,
     I              myTime, myThid )
      DO j=1-OLy,sNy+OLy
        DO i=1-OLx,sNx+OLx
          gT_arr(i,j) = gT_arr(i,j) + gT(i,j,k,bi,bj)
        ENDDO
      ENDDO

#else  /* USE_OLD_EXTERNAL_FORCING */

      IF ( fluidIsAir ) THEN
       kSurface = 0
      ELSEIF ( usingZCoords .AND. useShelfIce ) THEN
       kSurface = -1
      ELSEIF ( usingPCoords ) THEN
       kSurface = Nr
      ELSE
       kSurface = 1
      ENDIF
      recip_Cp = 1. _d 0 / HeatCapacity_Cp

C--   Note on loop range: For model dynamics, only needs to get correct
C     forcing (update gT_arr) in tile interior (1:sNx,1:sNy);
C     However, for some diagnostics, we may want to get valid forcing
C     extended over 1 point in tile halo region (0:sNx+1,0:sNy=1).

C--   Forcing term
#ifdef ALLOW_AIM
      IF ( useAIM ) CALL AIM_TENDENCY_APPLY_T(
     U                       gT_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_AIM */

#ifdef ALLOW_ATM_PHYS
      IF ( useAtm_Phys ) CALL ATM_PHYS_TENDENCY_APPLY_T(
     U                       gT_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_ATM_PHYS */

#ifdef ALLOW_FIZHI
      IF ( useFIZHI ) CALL FIZHI_TENDENCY_APPLY_T(
     U                       gT_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_FIZHI */

#ifdef ALLOW_ADDFLUID
      IF ( selectAddFluid.NE.0 .AND. temp_addMass.NE.UNSET_RL ) THEN
       IF ( ( selectAddFluid.GE.1 .AND. nonlinFreeSurf.GT.0 )
     &      .OR. convertFW2Salt.EQ.-1. _d 0 ) THEN
         DO j=0,sNy+1
          DO i=0,sNx+1
            gT_arr(i,j) = gT_arr(i,j)
     &        + addMass(i,j,k,bi,bj)*mass2rUnit
     &          *( temp_addMass - theta(i,j,k,bi,bj) )
     &          *recip_rA(i,j,bi,bj)
     &          *recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
C    &          *recip_deepFac2C(k)*recip_rhoFacC(k)
          ENDDO
         ENDDO
       ELSE
         DO j=0,sNy+1
          DO i=0,sNx+1
            gT_arr(i,j) = gT_arr(i,j)
     &        + addMass(i,j,k,bi,bj)*mass2rUnit
     &          *( temp_addMass - tRef(k) )
     &          *recip_rA(i,j,bi,bj)
     &          *recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
C    &          *recip_deepFac2C(k)*recip_rhoFacC(k)
          ENDDO
         ENDDO
       ENDIF
      ENDIF
#endif /* ALLOW_ADDFLUID */

#ifdef ALLOW_FRICTION_HEATING
      IF ( addFrictionHeating ) THEN
        IF ( fluidIsAir ) THEN
C         conversion from in-situ Temp to Pot.Temp
          tmpFac = (atm_Po/rC(k))**atm_kappa
C         conversion from W/m^2/r_unit to K/s
          tmpFac = (tmpFac/atm_Cp) * mass2rUnit
        ELSE
C         conversion from W/m^2/r_unit to K/s
          tmpFac = recip_Cp * mass2rUnit
        ENDIF
        DO j=0,sNy+1
          DO i=0,sNx+1
            gT_arr(i,j) = gT_arr(i,j)
     &         + frictionHeating(i,j,k,bi,bj)*tmpFac
     &          *recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
          ENDDO
        ENDDO
      ENDIF
#endif /* ALLOW_FRICTION_HEATING */

      IF ( fluidIsAir .AND. atm_Rq.NE.zeroRL .AND. Nr.NE.1 ) THEN
C--   Compressible fluid: account for difference between moist and dry air
C     specific volume in Enthalpy equation (+ V.dP term), since only the
C     dry air part is accounted for in the (dry) Pot.Temp formulation.
C     Used centered averaging from interface to center (consistent with
C     conversion term in KE eq) and same discretisation ( [T*Q]_bar_k )
C     as for Theta_v in CALC_PHI_HYD

C     conversion from in-situ Temp to Pot.Temp
        tmpFac = (atm_Po/rC(k))**atm_kappa
C     conversion from W/kg to K/s
        tmpFac = tmpFac/atm_Cp
        km = k-1
        kc = k
        kp = k+1
        IF ( k.EQ.1 ) THEN
          DO j=0,sNy+1
           DO i=0,sNx+1
            tmpVar(i,j) = 0.
           ENDDO
          ENDDO
        ELSE
          delPI = atm_Cp*( (rC(km)/atm_Po)**atm_kappa
     &                   - (rC(kc)/atm_Po)**atm_kappa )
          DO j=0,sNy+1
           DO i=0,sNx+1
            tmpVar(i,j) = wVel(i,j,kc,bi,bj)*delPI*atm_Rq
     &                  *( theta(i,j,km,bi,bj)*salt(i,j,km,bi,bj)
     &                   + theta(i,j,kc,bi,bj)*salt(i,j,kc,bi,bj)
     &                   )*maskC(i,j,km,bi,bj)*0.25 _d 0
           ENDDO
          ENDDO
        ENDIF
        IF ( k.LT.Nr ) THEN
          delPI = atm_Cp*( (rC(kc)/atm_Po)**atm_kappa
     &                   - (rC(kp)/atm_Po)**atm_kappa )
          DO j=0,sNy+1
           DO i=0,sNx+1
            tmpVar(i,j) = tmpVar(i,j)
     &                  + wVel(i,j,kp,bi,bj)*delPI*atm_Rq
     &                  *( theta(i,j,kc,bi,bj)*salt(i,j,kc,bi,bj)
     &                   + theta(i,j,kp,bi,bj)*salt(i,j,kp,bi,bj)
     &                   )*maskC(i,j,kp,bi,bj)*0.25 _d 0
           ENDDO
          ENDDO
        ENDIF
        DO j=0,sNy+1
          DO i=0,sNx+1
            gT_arr(i,j) = gT_arr(i,j)
     &         + tmpVar(i,j)*tmpFac
     &          *recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
          ENDDO
        ENDDO
#ifdef ALLOW_DIAGNOSTICS
        IF ( useDiagnostics ) THEN
C     conversion to W/m^2
          tmpFac = rUnit2mass
          CALL DIAGNOSTICS_SCALE_FILL( tmpVar, tmpFac, 1,
     &                     'MoistCor', kc, 1, 2, bi,bj,myThid )
        ENDIF
#endif /* ALLOW_DIAGNOSTICS */
      ENDIF

C     Ocean: Add temperature surface forcing (e.g., heat-flux) in surface level
      IF ( k .EQ. kSurface ) THEN
       DO j=0,sNy+1
        DO i=0,sNx+1
          gT_arr(i,j) = gT_arr(i,j)
     &      +surfaceForcingT(i,j,bi,bj)
     &      *recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
        ENDDO
       ENDDO
      ELSEIF ( kSurface.EQ.-1 ) THEN
       DO j=0,sNy+1
        DO i=0,sNx+1
         IF ( kSurfC(i,j,bi,bj).EQ.k ) THEN
          gT_arr(i,j) = gT_arr(i,j)
     &      +surfaceForcingT(i,j,bi,bj)
     &      *recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
         ENDIF
        ENDDO
       ENDDO
      ENDIF

      IF (linFSConserveTr) THEN
       DO j=0,sNy+1
        DO i=0,sNx+1
          IF (k .EQ. kSurfC(i,j,bi,bj)) THEN
            gT_arr(i,j) = gT_arr(i,j)
     &        +TsurfCor*recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
          ENDIF
        ENDDO
       ENDDO
      ENDIF

#ifdef ALLOW_GEOTHERMAL_FLUX
      IF ( usingZCoords ) THEN
       DO j=0,sNy+1
        DO i=0,sNx+1
         IF ( k.EQ.kLowC(i,j,bi,bj) ) THEN
          gT_arr(i,j)=gT_arr(i,j)
     &      + geothermalFlux(i,j,bi,bj)
     &        *recip_Cp*mass2rUnit
     &        *recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
         ENDIF
        ENDDO
       ENDDO
      ENDIF
#endif /* ALLOW_GEOTHERMAL_FLUX */

#ifdef SHORTWAVE_HEATING
C Penetrating SW radiation
c     IF ( usePenetratingSW ) THEN
       swfracb(1)=abs(rF(k))
       swfracb(2)=abs(rF(k+1))
       CALL SWFRAC(
     I             2, minusOne,
     U             swfracb,
     I             myTime, 1, myThid )
       kp1 = k+1
       IF (k.EQ.Nr) THEN
        kp1 = k
        swfracb(2)=0. _d 0
       ENDIF
       DO j=0,sNy+1
        DO i=0,sNx+1
         gT_arr(i,j) = gT_arr(i,j)
     &   -Qsw(i,j,bi,bj)*(swfracb(1)*maskC(i,j,k,bi,bj)
     &                   -swfracb(2)*maskC(i,j,kp1, bi,bj))
     &    *recip_Cp*mass2rUnit
     &    *recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
        ENDDO
       ENDDO
c     ENDIF
#endif

#ifdef ALLOW_FRAZIL
      IF ( useFRAZIL )
     &     CALL FRAZIL_TENDENCY_APPLY_T(
     U                 gT_arr,
     I                 iMin,iMax,jMin,jMax, k, bi,bj,
     I                 myTime, myIter, myThid )
#endif /* ALLOW_FRAZIL */

#ifdef ALLOW_SHELFICE
      IF ( useShelfIce )
     &     CALL SHELFICE_FORCING_T(
     U                   gT_arr,
     I                   iMin,iMax,jMin,jMax, k, bi,bj,
     I                   myTime, myIter, myThid )
#endif /* ALLOW_SHELFICE */

#ifdef ALLOW_ICEFRONT
      IF ( useICEFRONT )
     &     CALL ICEFRONT_TENDENCY_APPLY_T(
     U                   gT_arr,
     I                   k, bi, bj, myTime, myIter, myThid )
#endif /* ALLOW_ICEFRONT */

#ifdef ALLOW_SALT_PLUME
      IF ( useSALT_PLUME )
     &     CALL SALT_PLUME_TENDENCY_APPLY_T(
     U                     gT_arr,
     I                     iMin,iMax,jMin,jMax, k, bi,bj,
     I                     myTime, myIter, myThid )
#endif /* ALLOW_SALT_PLUME */

#ifdef ALLOW_RBCS
      IF (useRBCS) THEN
        CALL RBCS_ADD_TENDENCY(
     U                 gT_arr,
     I                 k, bi, bj, 1,
     I                 myTime, myIter, myThid )
      ENDIF
#endif /* ALLOW_RBCS */

#ifdef ALLOW_OBCS
      IF (useOBCS) THEN
        CALL OBCS_SPONGE_T(
     U                   gT_arr,
     I                   iMin,iMax,jMin,jMax, k, bi,bj,
     I                   myTime, myIter, myThid )
      ENDIF
#endif /* ALLOW_OBCS */

#ifdef ALLOW_BBL
      IF ( useBBL ) CALL BBL_TENDENCY_APPLY_T(
     U                       gT_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_BBL */

#ifdef ALLOW_MYPACKAGE
      IF ( useMYPACKAGE ) THEN
        CALL MYPACKAGE_TENDENCY_APPLY_T(
     U                 gT_arr,
     I                 iMin,iMax,jMin,jMax, k, bi,bj,
     I                 myTime, myIter, myThid )
      ENDIF
#endif /* ALLOW_MYPACKAGE */

#endif /* USE_OLD_EXTERNAL_FORCING */

      RETURN
      END

C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
CBOP
C     !ROUTINE: APPLY_FORCING_S
C     !INTERFACE:
      SUBROUTINE APPLY_FORCING_S(
     U                     gS_arr,
     I                     iMin,iMax,jMin,jMax, k, bi, bj,
     I                     myTime, myIter, myThid )
C     !DESCRIPTION: \bv
C     *==========================================================*
C     | S/R APPLY_FORCING_S
C     | o Contains problem specific forcing for merid velocity.
C     *==========================================================*
C     | Adds terms to gS for forcing by external sources
C     | e.g. fresh-water flux, climatalogical relaxation, etc ...
C     *==========================================================*
C     \ev

C     !USES:
      IMPLICIT NONE
C     == Global data ==
#include "SIZE.h"
#include "EEPARAMS.h"
#include "PARAMS.h"
#include "GRID.h"
#include "DYNVARS.h"
#include "FFIELDS.h"
#include "SURFACE.h"

C     !INPUT/OUTPUT PARAMETERS:
C     gS_arr    :: the tendency array
C     iMin,iMax :: Working range of x-index for applying forcing.
C     jMin,jMax :: Working range of y-index for applying forcing.
C     k         :: Current vertical level index
C     bi,bj     :: Current tile indices
C     myTime    :: Current time in simulation
C     myIter    :: Current iteration number
C     myThid    :: my Thread Id number
      _RL     gS_arr(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      INTEGER iMin, iMax, jMin, jMax
      INTEGER k, bi, bj
      _RL     myTime
      INTEGER myIter
      INTEGER myThid

C     !LOCAL VARIABLES:
C     i,j       :: Loop counters
C     kSurface  :: index of surface level
      INTEGER i, j
#ifndef USE_OLD_EXTERNAL_FORCING
      INTEGER kSurface
#endif /* USE_OLD_EXTERNAL_FORCING */
CEOP

#ifdef USE_OLD_EXTERNAL_FORCING

      DO j=1-OLy,sNy+OLy
        DO i=1-OLx,sNx+OLx
          gS(i,j,k,bi,bj) = 0. _d 0
        ENDDO
      ENDDO
      CALL EXTERNAL_FORCING_S(
     I              iMin, iMax, jMin, jMax, bi, bj, k,
     I              myTime, myThid )
      DO j=1-OLy,sNy+OLy
        DO i=1-OLx,sNx+OLx
          gS_arr(i,j) = gS_arr(i,j) + gS(i,j,k,bi,bj)
        ENDDO
      ENDDO

#else  /* USE_OLD_EXTERNAL_FORCING */

      IF ( fluidIsAir ) THEN
       kSurface = 0
      ELSEIF ( usingZCoords .AND. useShelfIce ) THEN
       kSurface = -1
      ELSEIF ( usingPCoords ) THEN
       kSurface = Nr
      ELSE
       kSurface = 1
      ENDIF

C--   Note on loop range: For model dynamics, only needs to get correct
C     forcing (update gS_arr) in tile interior (1:sNx,1:sNy);
C     However, for some diagnostics, we may want to get valid forcing
C     extended over 1 point in tile halo region (0:sNx+1,0:sNy=1).

C--   Forcing term
#ifdef ALLOW_AIM
      IF ( useAIM ) CALL AIM_TENDENCY_APPLY_S(
     U                       gS_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_AIM */

#ifdef ALLOW_ATM_PHYS
      IF ( useAtm_Phys ) CALL ATM_PHYS_TENDENCY_APPLY_S(
     U                       gS_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_ATM_PHYS */

#ifdef ALLOW_FIZHI
      IF ( useFIZHI ) CALL FIZHI_TENDENCY_APPLY_S(
     U                       gS_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_FIZHI */

#ifdef ALLOW_ADDFLUID
      IF ( selectAddFluid.NE.0 .AND. salt_addMass.NE.UNSET_RL ) THEN
       IF ( ( selectAddFluid.GE.1 .AND. nonlinFreeSurf.GT.0 )
     &      .OR. convertFW2Salt.EQ.-1. _d 0 ) THEN
         DO j=0,sNy+1
          DO i=0,sNx+1
            gS_arr(i,j) = gS_arr(i,j)
     &        + addMass(i,j,k,bi,bj)*mass2rUnit
     &          *( salt_addMass - salt(i,j,k,bi,bj) )
     &          *recip_rA(i,j,bi,bj)
     &          *recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
C    &          *recip_deepFac2C(k)*recip_rhoFacC(k)
          ENDDO
         ENDDO
       ELSE
         DO j=0,sNy+1
          DO i=0,sNx+1
            gS_arr(i,j) = gS_arr(i,j)
     &        + addMass(i,j,k,bi,bj)*mass2rUnit
     &          *( salt_addMass - sRef(k) )
     &          *recip_rA(i,j,bi,bj)
     &          *recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
C    &          *recip_deepFac2C(k)*recip_rhoFacC(k)
          ENDDO
         ENDDO
       ENDIF
      ENDIF
#endif /* ALLOW_ADDFLUID */

C     Ocean: Add salinity surface forcing (e.g., fresh-water) in surface level
      IF ( k .EQ. kSurface ) THEN
       DO j=0,sNy+1
        DO i=0,sNx+1
          gS_arr(i,j) = gS_arr(i,j)
     &      +surfaceForcingS(i,j,bi,bj)
     &      *recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
        ENDDO
       ENDDO
      ELSEIF ( kSurface.EQ.-1 ) THEN
       DO j=0,sNy+1
        DO i=0,sNx+1
         IF ( kSurfC(i,j,bi,bj).EQ.k ) THEN
          gS_arr(i,j) = gS_arr(i,j)
     &      +surfaceForcingS(i,j,bi,bj)
     &      *recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
         ENDIF
        ENDDO
       ENDDO
      ENDIF

      IF (linFSConserveTr) THEN
       DO j=0,sNy+1
        DO i=0,sNx+1
          IF (k .EQ. kSurfC(i,j,bi,bj)) THEN
            gS_arr(i,j) = gS_arr(i,j)
     &        +SsurfCor*recip_drF(k)*_recip_hFacC(i,j,k,bi,bj)
          ENDIF
        ENDDO
       ENDDO
      ENDIF

#ifdef ALLOW_SHELFICE
      IF ( useShelfIce )
     &     CALL SHELFICE_FORCING_S(
     U                   gS_arr,
     I                   iMin,iMax,jMin,jMax, k, bi,bj,
     I                   myTime, myIter, myThid )
#endif /* ALLOW_SHELFICE */

#ifdef ALLOW_ICEFRONT
      IF ( useICEFRONT )
     &     CALL ICEFRONT_TENDENCY_APPLY_S(
     U                   gS_arr,
     I                   k, bi, bj, myTime, myIter, myThid )
#endif /* ALLOW_ICEFRONT */

#ifdef ALLOW_SALT_PLUME
      IF ( useSALT_PLUME )
     &     CALL SALT_PLUME_TENDENCY_APPLY_S(
     U                     gS_arr,
     I                     iMin,iMax,jMin,jMax, k, bi,bj,
     I                     myTime, myIter, myThid )
#endif /* ALLOW_SALT_PLUME */

#ifdef ALLOW_RBCS
      IF (useRBCS) THEN
        CALL RBCS_ADD_TENDENCY(
     U                 gS_arr,
     I                 k, bi, bj, 2,
     I                 myTime, myIter, myThid )
      ENDIF
#endif /* ALLOW_RBCS */

#ifdef ALLOW_OBCS
      IF (useOBCS) THEN
        CALL OBCS_SPONGE_S(
     U                   gS_arr,
     I                   iMin,iMax,jMin,jMax, k, bi,bj,
     I                   myTime, myIter, myThid )
      ENDIF
#endif /* ALLOW_OBCS */

#ifdef ALLOW_BBL
      IF ( useBBL ) CALL BBL_TENDENCY_APPLY_S(
     U                       gS_arr,
     I                       iMin,iMax,jMin,jMax, k, bi,bj,
     I                       myTime, myIter, myThid )
#endif /* ALLOW_BBL */

#ifdef ALLOW_MYPACKAGE
      IF ( useMYPACKAGE ) THEN
        CALL MYPACKAGE_TENDENCY_APPLY_S(
     U                 gS_arr,
     I                 iMin,iMax,jMin,jMax, k, bi,bj,
     I                 myTime, myIter, myThid )
      ENDIF
#endif /* ALLOW_MYPACKAGE */

#endif /* USE_OLD_EXTERNAL_FORCING */

      RETURN
      END