! $Id: dissip.F90 5103 2024-07-23 13:29:36Z abarral $

SUBROUTINE dissip(vcov, ucov, teta, p, dv, du, dh)
  !
  USE comconst_mod, ONLY: dtdiss

  IMPLICIT NONE


  ! ..  Avec nouveaux operateurs star :  gradiv2 , divgrad2, nxgraro2  ...
  ! (  10/01/98  )

  !=======================================================================
  !
  !   Auteur:  P. Le Van
  !   -------
  !
  !   Objet:
  !   ------
  !
  !   Dissipation horizontale
  !
  !=======================================================================
  !-----------------------------------------------------------------------
  !   Declarations:
  !   -------------

  include "dimensions.h"
  include "paramet.h"
  include "comgeom.h"
  include "comdissnew.h"
  include "comdissipn.h"

  !   Arguments:
  !   ----------

  REAL, INTENT(IN) :: vcov(ip1jm, llm) ! covariant meridional wind
  REAL, INTENT(IN) :: ucov(ip1jmp1, llm) ! covariant zonal wind
  REAL, INTENT(IN) :: teta(ip1jmp1, llm) ! potential temperature
  REAL, INTENT(IN) :: p(ip1jmp1, llmp1) ! pressure
  ! ! tendencies (.../s) on covariant winds and potential temperature
  REAL, INTENT(OUT) :: dv(ip1jm, llm)
  REAL, INTENT(OUT) :: du(ip1jmp1, llm)
  REAL, INTENT(OUT) :: dh(ip1jmp1, llm)

  !   Local:
  !   ------

  REAL :: gdx(ip1jmp1, llm), gdy(ip1jm, llm)
  REAL :: grx(ip1jmp1, llm), gry(ip1jm, llm)
  REAL :: te1dt(llm), te2dt(llm), te3dt(llm)
  REAL :: deltapres(ip1jmp1, llm)

  INTEGER :: l, ij

  REAL :: SSUM

  !-----------------------------------------------------------------------
  !   initialisations:
  !   ----------------

  DO l = 1, llm
    te1dt(l) = tetaudiv(l) * dtdiss
    te2dt(l) = tetaurot(l) * dtdiss
    te3dt(l) = tetah(l) * dtdiss
  ENDDO
  du = 0.
  dv = 0.
  dh = 0.

  !-----------------------------------------------------------------------
  !   Calcul de la dissipation:
  !   -------------------------

  !   Calcul de la partie   grad  ( div ) :
  !   -------------------------------------

  IF(lstardis) THEN
    CALL gradiv2(llm, ucov, vcov, nitergdiv, gdx, gdy)
  ELSE
    CALL gradiv (llm, ucov, vcov, nitergdiv, gdx, gdy)
  ENDIF

  DO l = 1, llm

    DO ij = 1, iip1
      gdx(ij, l) = 0.
      gdx(ij + ip1jm, l) = 0.
    ENDDO

    DO ij = iip2, ip1jm
      du(ij, l) = du(ij, l) - te1dt(l) * gdx(ij, l)
    ENDDO
    DO ij = 1, ip1jm
      dv(ij, l) = dv(ij, l) - te1dt(l) * gdy(ij, l)
    ENDDO

  ENDDO

  !   calcul de la partie   n X grad ( rot ):
  !   ---------------------------------------

  IF(lstardis) THEN
    CALL nxgraro2(llm, ucov, vcov, nitergrot, grx, gry)
  ELSE
    CALL nxgrarot(llm, ucov, vcov, nitergrot, grx, gry)
  ENDIF

  DO l = 1, llm
    DO ij = 1, iip1
      grx(ij, l) = 0.
    ENDDO

    DO ij = iip2, ip1jm
      du(ij, l) = du(ij, l) - te2dt(l) * grx(ij, l)
    ENDDO
    DO ij = 1, ip1jm
      dv(ij, l) = dv(ij, l) - te2dt(l) * gry(ij, l)
    ENDDO
  ENDDO

  !   calcul de la partie   div ( grad ):
  !   -----------------------------------

  IF(lstardis) THEN

    DO l = 1, llm
      DO ij = 1, ip1jmp1
        deltapres(ij, l) = AMAX1(0., p(ij, l) - p(ij, l + 1))
      ENDDO
    ENDDO

    CALL divgrad2(llm, teta, deltapres, niterh, gdx)
  ELSE
    CALL divgrad (llm, teta, niterh, gdx)
  ENDIF

  DO l = 1, llm
    DO ij = 1, ip1jmp1
      dh(ij, l) = dh(ij, l) - te3dt(l) * gdx(ij, l)
    ENDDO
  ENDDO

  RETURN
END SUBROUTINE dissip