SUBROUTINE alpale_wk(dtime, cell_area, zoccur, sigmaw, wdens, fip, &
        fip_cond)

  ! **************************************************************
  !                                                              *
  ! ALPALE_WK                                                    *
  !                                                              *
  !                                                              *
  ! written by   : Jean-Yves Grandpeix, 07/08/2017               *
  ! modified by :                                                *
  ! **************************************************************

  USE dimphy, ONLY: klon
  USE lmdz_ioipsl_getin_p, ONLY: getin_p
  USE lmdz_print_control, ONLY: mydebug => debug, lunout, prt_level
  USE lmdz_yomcst, ONLY: rpi

  IMPLICIT NONE

  !================================================================
  ! Auteur(s)   : Jean-Yves Grandpeix, 07/08/2017
  ! Objet : Contribution of the wake scheme to Ale and Alp
  !================================================================

  ! Input arguments
  !----------------
  REAL, INTENT(IN) :: dtime
  REAL, DIMENSION(klon), INTENT(IN) :: cell_area
  INTEGER, DIMENSION(klon), INTENT (IN) :: zoccur
  REAL, DIMENSION(klon), INTENT(IN) :: sigmaw
  REAL, DIMENSION(klon), INTENT(IN) :: wdens
  REAL, DIMENSION(klon), INTENT(IN) :: fip
  ! Output arguments
  !-----------------
  REAL, DIMENSION(klon), INTENT(OUT) :: fip_cond


  ! Local variables
  !----------------
  INTEGER :: i
  LOGICAL, SAVE :: first = .TRUE.
  !$OMP THREADPRIVATE(first)
  REAL, ALLOCATABLE, SAVE, DIMENSION(:) :: cellrad
  !$OMP THREADPRIVATE(cellrad)
  REAL, DIMENSION(klon) :: wkrad
  REAL, DIMENSION(klon) :: proba_gf

  IF (first) THEN
    ALLOCATE (cellrad(klon))
    !  Compute pseudo grid-cell radius cellrad, such that pi*cellrad^2=cell_area
    print *, 'alpale_wk: cell_area(1) ', cell_area(1)
    cellrad(:) = sqrt(cell_area(:) / rpi)
    first = .FALSE.
  ENDIF

  !  Compute wake radius
  !!  print *,'alpale_wk: sigmaw(1), wdens(1) ', sigmaw(1), wdens(1)
  DO i = 1, klon
    IF (zoccur(i) >= 1) THEN
      wkrad(i) = sqrt(sigmaw(i) / (rpi * wdens(i)))
    ELSE
      wkrad(i) = 0.
    ENDIF ! (zoccur(i) .GE. 1)
  ENDDO

  !  Compute probability that the grid-cell is intersected by a gust front
  !!  print *,'alpale_wk: wkrad(1), cellrad(1) ', wkrad(1), cellrad(1)
  !!  proba_gf(:) = exp(-wdens(:)*rpi*max(wkrad(:)-cellrad(:),0.)**2) - &   ! Formules
  !!                exp(-wdens(:)*rpi*(wkrad(:)+cellrad(:))**2)             ! fausses !
  proba_gf(:) = 1. - exp(-wdens(:) * rpi * ((wkrad(:) + cellrad(:))**2 - &
          max(wkrad(:) - cellrad(:), 0.)**2))

  proba_gf(:) = max(proba_gf(:), 1.e-3)
  !  Compute Fip conditionned on the presence of some gust front within the
  !  grid-cell
  !!  print *,'alpale_wk: proba_gf(1), fip(1), ', proba_gf(1), fip(1)
  fip_cond(:) = fip(:) / proba_gf(:)
  !!    print *,'alpale_wk: wkrad(1), cellrad(1), proba_gf(1), fip(1), fip_cond(1) ', &
  !!                        wkrad(1), cellrad(1), proba_gf(1), fip(1), fip_cond(1)

END SUBROUTINE alpale_wk