!--------------------------------------------------------------------------
   !---------------------------- caldyn_fast ----------------------------------
   !
   SELECT CASE(caldyn_thermo)
   CASE(thermo_boussinesq)
      DO l = ll_begin, ll_end
         !DIR$ SIMD
         DO ij=ij_begin, ij_end
            berni(ij,l) = pk(ij,l)
            ! from now on pk contains the vertically-averaged geopotential
            pk(ij,l) = .5*(geopot(ij,l)+geopot(ij,l+1))
         END DO
      END DO
   CASE(thermo_theta)
      DO l = ll_begin, ll_end
         !DIR$ SIMD
         DO ij=ij_begin, ij_end
            berni(ij,l) = .5*(geopot(ij,l)+geopot(ij,l+1))
         END DO
      END DO
   CASE(thermo_entropy)
      DO l = ll_begin, ll_end
         !DIR$ SIMD
         DO ij=ij_begin, ij_end
            berni(ij,l) = .5*(geopot(ij,l)+geopot(ij,l+1))
            berni(ij,l) = berni(ij,l) + pk(ij,l)*(cpp-theta(ij,l,1)) ! Gibbs = Cp.T-Ts = T(Cp-s)
         END DO
      END DO
   CASE DEFAULT
      PRINT *, 'Unsupported value of caldyn_thermo : ',caldyn_thermo ! FIXME
      STOP
   END SELECT
   !
   DO l = ll_begin, ll_end
      !DIR$ SIMD
      DO ij=ij_begin, ij_end
         due = .5*(theta(ij,l,1)+theta(ij+t_right,l,1))*(pk(ij+t_right,l)-pk(ij,l)) + berni(ij+t_right,l)-berni(ij,l)
         du(ij+u_right,l) = du(ij+u_right,l) - ne_right*due
         u(ij+u_right,l) = u(ij+u_right,l) + tau*du(ij+u_right,l)
         due = .5*(theta(ij,l,1)+theta(ij+t_lup,l,1))*(pk(ij+t_lup,l)-pk(ij,l)) + berni(ij+t_lup,l)-berni(ij,l)
         du(ij+u_lup,l) = du(ij+u_lup,l) - ne_lup*due
         u(ij+u_lup,l) = u(ij+u_lup,l) + tau*du(ij+u_lup,l)
         due = .5*(theta(ij,l,1)+theta(ij+t_ldown,l,1))*(pk(ij+t_ldown,l)-pk(ij,l)) + berni(ij+t_ldown,l)-berni(ij,l)
         du(ij+u_ldown,l) = du(ij+u_ldown,l) - ne_ldown*due
         u(ij+u_ldown,l) = u(ij+u_ldown,l) + tau*du(ij+u_ldown,l)
      END DO
   END DO
   !
   !---------------------------- caldyn_fast ----------------------------------
   !--------------------------------------------------------------------------