cavity_salt_fluxes Subroutine

   pure subroutine cavity_salt_fluxes(const, S_w, S_b, m_mass, gamma_s, S_i, &
                                      f_turb, f_phase)
      !! The two sides of (E3), in (g/kg)*kg/m^2/s:
      !!
      !!   `f_turb  = rho_w*gamma_s*(S_w - S_b)`  turbulent salt flux
      !!                                          toward the interface
      !!   `f_phase = m_mass*(S_b - S_i)`         salt rejected/diluted by
      !!                                          the phase change
      !!
      !! (E3) says these are equal; the unit tests assert it to round-off.
      !$acc routine seq
      type(ocean_cavity_const_t), intent(in) :: const
         !! Constants bundle — `rho_w`.
      real(wp), intent(in) :: S_w
         !! Far-field salinity (g/kg).
      real(wp), intent(in) :: S_b
         !! Interface salinity (g/kg).
      real(wp), intent(in) :: m_mass
         !! Melt mass flux (kg/m^2/s).
      real(wp), intent(in) :: gamma_s
         !! Salt exchange velocity (m/s).
      real(wp), intent(in) :: S_i
         !! Ice salinity (g/kg).
      real(wp), intent(out) :: f_turb
         !! Turbulent salt flux toward the interface.
      real(wp), intent(out) :: f_phase
         !! Phase-change salt flux.
      f_turb = const%rho_w*gamma_s*(S_w - S_b)
      f_phase = m_mass*(S_b - S_i)
   end subroutine cavity_salt_fluxes