*           rr_flux_sz.F
*
*           Rick Romea
*           Jan. 24, 2000      
*
*     Zonal nonlinear advective flux term:  - d(wS)/dz
*     Units :  (SALINITY(ppm) - 0.035) / s
*     MOM2 Grid:  T   
*
*******************************************************************

      SUBROUTINE RR_flux_sz_init(id)
	IMPLICIT NONE
      INCLUDE 'ferret_cmn/EF_Util.cmn'
      INTEGER id

      CALL ef_set_desc             (id,
     .'-d(wS)/dz advective momentum: flux-form (SALT/s);MOM2 T Grid')
      CALL ef_set_num_args         (id, 3)
      CALL ef_set_axis_inheritance (id, IMPLIED_BY_ARGS, 
     .                                  IMPLIED_BY_ARGS, 
     .                                  IMPLIED_BY_ARGS, 
     .                                  IMPLIED_BY_ARGS)
      CALL ef_set_piecemeal_ok     (id, NO, NO, NO, NO)

      ! Define first argument (U)

      CALL ef_set_arg_name         (id, ARG1, 'U')
      CALL ef_set_arg_desc         (id, ARG1,
     . 'Zonal velocity, on the MOM2 U Grid. ')
      CALL ef_set_arg_unit         (id, ARG1, 'cm/sec')
      CALL ef_set_arg_type         (id, ARG1, FLOAT_ARG)
      CALL ef_set_axis_influence   (id, ARG1, YES, YES, YES, YES)
      CALL ef_set_axis_extend      (id, ARG1, X_AXIS,-1,+1)
      CALL ef_set_axis_extend      (id, ARG1, Y_AXIS,-1,+1)
      CALL ef_set_axis_extend      (id, ARG1, Z_AXIS,0,+1)

      ! Define second argument (W)

      CALL ef_set_arg_name         (id, ARG2, 'W')
      CALL ef_set_arg_desc         (id, ARG2,
     . 'Vertical velocity, at T cell bottom on the MOM2 Grid. ')
      CALL ef_set_arg_unit         (id, ARG2, 'cm/sec')
      CALL ef_set_arg_type         (id, ARG2, FLOAT_ARG)
      CALL ef_set_axis_influence   (id, ARG2, NO, NO, NO, YES)
      CALL ef_set_axis_extend      (id, ARG2, X_AXIS,-1,+1)
      CALL ef_set_axis_extend      (id, ARG2, Y_AXIS,-1,+1)
      CALL ef_set_axis_extend      (id, ARG2, Z_AXIS,0,+1)

      ! Define third argument (SALT)

      CALL ef_set_arg_name         (id, ARG3, 'SALT')
      CALL ef_set_arg_desc         (id, ARG3,
     . 'Salinity, on the MOM2 T Grid. ')
      CALL ef_set_arg_unit         (id, ARG3,
     . '(SALINITY(ppt) - 35) /1000')
      CALL ef_set_arg_type         (id, ARG3, FLOAT_ARG)
      CALL ef_set_axis_influence   (id, ARG3, NO, NO,YES,YES)
      CALL ef_set_axis_extend      (id, ARG3, X_AXIS,-1,+1)
      CALL ef_set_axis_extend      (id, ARG3, Y_AXIS,-1,+1)
      CALL ef_set_axis_extend      (id, ARG3, Z_AXIS,0,+1)

      END




      SUBROUTINE RR_flux_sz_compute(id, arg_1, arg_2, arg_3, result)
      IMPLICIT NONE
      INCLUDE 'ferret_cmn/EF_Util.cmn'
      INCLUDE 'ferret_cmn/EF_mem_subsc.cmn'

      INTEGER        id

      REAL           bad_flag(EF_MAX_ARGS)
      REAL           bad_flag_result
      REAL           arg_1 (mem1lox:mem1hix, mem1loy:mem1hiy, 
     .                      mem1loz:mem1hiz, mem1lot:mem1hit)
      REAL           arg_2 (mem2lox:mem2hix, mem2loy:mem2hiy, 
     .                      mem2loz:mem2hiz, mem2lot:mem2hit)
      REAL           arg_3 (mem3lox:mem3hix, mem3loy:mem3hiy, 
     .                      mem3loz:mem3hiz, mem3lot:mem3hit)
      REAL           result (memreslox:memreshix,memresloy:memreshiy,
     .                       memresloz:memreshiz,memreslot:memreshit)

      INTEGER        res_lo_ss (4)
      INTEGER        res_hi_ss (4)
      INTEGER        res_incr  (4)

      INTEGER        arg_lo_ss (4,EF_MAX_ARGS)
      INTEGER        arg_hi_ss (4,EF_MAX_ARGS)
      INTEGER        arg_incr  (4,EF_MAX_ARGS)

      INTEGER        i,  j,  k,  l
      INTEGER        i2, j2, k2, l2
      INTEGER        i3, j3, k3, l3

      REAL*8         yU(1024)
      REAL*8         xU(1024)
      REAL*8         zW(1024)
      REAL*8         yT(1024)
      REAL*8         xT(1024)

      INTEGER        ilat
      INTEGER        ilon
      INTEGER        iZ

      CHARACTER*16   ax_name(4)
      CHARACTER*16   ax_units(4)
      LOGICAL        backward(4)
      LOGICAL        modulo(4)
      LOGICAL        regular(4)

      REAL           dxt, dyt, dxu, dyu
      REAL           dus, dun, duw, due
      REAL           adv_fb         
      INCLUDE 'rr_parameters.h'

C*********************************************************************
C
c     dzt     = vertical height of "u,v" or "t" grid box (in cm)
c     dyt     = latitudinal height of "t" grid box (in cm)
c     dxt     = longitudinal width of "t" grid box at the equator (cm)
c     dxu     = longitudinal width of "u,v" grid box at the equator (cm) 
c     dyu     = latitudinal height of "u,v" grid box (cm)
C
c     dus     = yu(j) - yt(j)
c     dun     = yt(j+1) - yu(j)
c     duw     = xu(i) - xt(i)
c     due     = xt(i+1) - xu(i)
C
c     yu(j)   = latitude of the jth "u,v" point in degrees 
c     yt(j)   = latitude of the jth "t" point in degrees   
c     xt(i)   = longitude of the ith "t" point in degrees  
c     xu(i)   = longitude of the ith "u,v" point in degrees
C 
C*********************************************************************

      dxt(i) = SNGL (xU(i)   - xU(i-1)) * Longitude_to_cm
      dyt(j) = SNGL (yU(j)   - yU(j-1)) * Latitude_to_cm
      dxu(i) = SNGL (xT(i+1) - xT(i))   * Longitude_to_cm
      dyu(j) = SNGL (yT(j+1) - yT(j))   * Latitude_to_cm
      dus(j) = SNGL (yU(j)   - yT(j))   * Latitude_to_cm
      dun(j) = SNGL (yT(j+1) - yU(j))   * Latitude_to_cm
      duw(i) = SNGL (xU(i)   - xT(i))   * Longitude_to_cm
      due(i) = SNGL (xT(i+1) - xU(i))   * Longitude_to_cm

      adv_fb(i2,j2,k2,l2,i3,j3,k3,l3) =  arg_2(i2,j2,k2,l2)
     .                  * (arg_3(i3,j3,k3,l3) + arg_3(i3,j3,k3+1,l3))

      CALL ef_get_res_subscripts (id, res_lo_ss, res_hi_ss, res_incr)
      CALL ef_get_arg_subscripts (id, arg_lo_ss, arg_hi_ss, arg_incr)
      CALL ef_get_bad_flags      (id, bad_flag,  bad_flag_result)
      CALL ef_get_coordinates    (id, ARG1, X_AXIS, 
     .                            arg_lo_ss(X_AXIS,ARG1),
     .                            arg_hi_ss(X_AXIS,ARG1), xU)
      CALL ef_get_coordinates    (id, ARG1, Y_AXIS, 
     .                            arg_lo_ss(Y_AXIS,ARG1),
     .                            arg_hi_ss(Y_AXIS,ARG1), yU)
      CALL ef_get_coordinates    (id, ARG2, Z_AXIS, 
     .                            arg_lo_ss(Z_AXIS,ARG2),
     .                            arg_hi_ss(Z_AXIS,ARG2), zW)
      CALL ef_get_coordinates    (id, ARG3, X_AXIS, 
     .                            arg_lo_ss(X_AXIS,ARG3),
     .                            arg_hi_ss(X_AXIS,ARG3), xT)
      CALL ef_get_coordinates    (id, ARG3, Y_AXIS, 
     .                            arg_lo_ss(Y_AXIS,ARG3),
     .                            arg_hi_ss(Y_AXIS,ARG3), yT)
      CALL ef_get_axis_info  (id, ARG1, ax_name, ax_units, 
     .                                backward, modulo, regular) 
      IF     ( ax_units(1) .NE. 'deg'       .AND.
     .         ax_units(1) .NE. 'lon'       .AND.
     .         ax_units(1) .NE. 'degrees_E' .AND.
     .         ax_units(1) .NE. 'longitude' .AND.
     .         ax_units(1) .NE. 'Longitude' .AND. 
     .         ax_units(1) .NE. 'LONGITUDE' ) THEN
        WRITE (6,*)'Longitude axis units =', ax_units(1) 
        !CALL ef_bail_out(id,'Longitude axis must be in degrees')
      ENDIF

      IF     ( ax_units(2) .NE. 'deg'       .AND.
     .         ax_units(2) .NE. 'degrees_N' .AND.
     .         ax_units(2) .NE. 'lat'       .AND.
     .         ax_units(2) .NE. 'latitude'  .AND.
     .         ax_units(2) .NE. 'Latitude'  .AND. 
     .         ax_units(2) .NE. 'LATITUDE' ) THEN
        WRITE (6,*)'Latitude axis units =', ax_units(2) 
        !CALL ef_bail_out(id,'Latitude axis must be in degrees')
      ENDIF
      CALL ef_get_axis_info  (id, ARG1, ax_name, ax_units, 
     .                                backward, modulo, regular) 
      IF     ( ax_units(3) .NE. 'm'           .AND.
     .         ax_units(3) .NE. 'meters'  .AND.
     .         ax_units(3) .NE. 'M'           .AND.
     .         ax_units(3) .NE. 'METERS' ) THEN
        WRITE (6,*)'Longitude axis units =', ax_units(1) 
        !CALL ef_bail_out(id,'Z axis must be in meters')
      ENDIF 


      l2 = arg_lo_ss(T_AXIS,ARG2) 
      l3 = arg_lo_ss(T_AXIS,ARG3) 
      DO l = res_lo_ss(T_AXIS), res_hi_ss(T_AXIS)

         ilat = 2  
         j2 = arg_lo_ss(Y_AXIS,ARG2) + 1
         j3 = arg_lo_ss(Y_AXIS,ARG3) + 1
         DO j = res_lo_ss(Y_AXIS), res_hi_ss(Y_AXIS)
         
            iLon = 2
            i2 = arg_lo_ss(X_AXIS,ARG2) + 1
            i3 = arg_lo_ss(X_AXIS,ARG3) + 1
            DO i = res_lo_ss(X_AXIS), res_hi_ss(X_AXIS)

	         iZ = 1
               k2 = arg_lo_ss(Z_AXIS,ARG2)
               k3 = arg_lo_ss(Z_AXIS,ARG3)
               DO k = res_lo_ss(Z_AXIS), res_hi_ss(Z_AXIS)

                  IF (arg_2(i2,  j2,  k2,l2) .EQ. bad_flag(ARG2) .OR.
     .                arg_2(i2+1,j2,  k2,l2) .EQ. bad_flag(ARG2) .OR.
     .                arg_2(i2-1,j2,  k2,l2) .EQ. bad_flag(ARG2) .OR.
     .                arg_2(i2,  j2+1,k2,l2) .EQ. bad_flag(ARG2) .OR.
     .                arg_2(i2+1,j2+1,k2,l2) .EQ. bad_flag(ARG2) .OR.
     .                arg_2(i2-1,j2+1,k2,l2) .EQ. bad_flag(ARG2) .OR.
     .                arg_2(i2,  j2-1,k2,l2) .EQ. bad_flag(ARG2) .OR.
     .                arg_2(i2+1,j2-1,k2,l2) .EQ. bad_flag(ARG2) .OR.
     .                arg_2(i2-1,j2-1,k2,l2) .EQ. bad_flag(ARG2) .OR.
     .                arg_3(i3,  j3,  k3,l3) .EQ. bad_flag(ARG3) .OR.
     .                arg_3(i3+1,j3,  k3,l3) .EQ. bad_flag(ARG3) .OR.
     .                arg_3(i3-1,j3,  k3,l3) .EQ. bad_flag(ARG3) .OR.
     .                arg_3(i3,  j3+1,k3,l3) .EQ. bad_flag(ARG3) .OR.
     .                arg_3(i3+1,j3+1,k3,l3) .EQ. bad_flag(ARG3) .OR.
     .                arg_3(i3-1,j3+1,k3,l3) .EQ. bad_flag(ARG3) .OR.
     .                arg_3(i3,  j3-1,k3,l3) .EQ. bad_flag(ARG3) .OR.
     .                arg_3(i3+1,j3-1,k3,l3) .EQ. bad_flag(ARG3) .OR.
     .                arg_3(i3-1,j3-1,k3,l3) .EQ. bad_flag(ARG3)) THEN
                     result(i,j,k,l) = bad_flag_result
                  ELSE
                     IF (iZ .EQ. 1) THEN
                        result(i,j,k,l) =  
     .                           adv_fb(i2,j2,k2,l2,i3,j3,k3,l3)
     .                             / 2. / (zW(iZ)*Meters_to_cm)       
     .                              * sec_per_month
                     ELSE
                        result(i,j,k,l) = - ( 
     .      	                    adv_fb(i2,j2,k2-1,l2,i3,j3,k3-1,l3)
     .                          - adv_fb(i2,j2,k2,  l2,i3,j3,k3,  l3))
     .                         / 2. / (zW(iZ-1)-zW(iZ))/Meters_to_cm 
     .                            * sec_per_month
                     ENDIF
                  ENDIF

	            iZ = iZ + 1
                  k2 = k2 + arg_incr(Z_AXIS,ARG2)
                  k3 = k3 + arg_incr(Z_AXIS,ARG3)
               ENDDO

               iLon = iLon + 1
               i2 = i2 + arg_incr(X_AXIS,ARG2)
               i3 = i3 + arg_incr(X_AXIS,ARG3)
            ENDDO

            iLat = iLat + 1
            j2 = j2 + arg_incr(Y_AXIS,ARG2)
            j3 = j3 + arg_incr(Y_AXIS,ARG3)
         ENDDO

         l2 = l2 + arg_incr(T_AXIS,ARG2)
         l3 = l3 + arg_incr(T_AXIS,ARG3)
      ENDDO               
      END

