!-----------------------------------------
      ! II.1 Define frequency of output and means
      ! -----------------------------------------
#if defined key_diainstant
      zsto = nwrite*rdt
      clop ="inst(only(x))"
#else
      zsto = rdt
      clop ="ave(x)"
#endif
      zout = ntrd*rdt

      IF( kt == nit000 ) THEN
         IF(lwp) WRITE (numout,*) ' Diavor: netCDF initialization'

         ! II.2 Compute julian date from starting date of the run
         ! ------------------------
         CALL ymds2ju( nyear, nmonth, nday, 0.e0, zjulian )
         IF (lwp) WRITE(numout,*)' '  
         IF (lwp) WRITE(numout,*)' Date 0 used :',nit000         &
              ,' YEAR ', nyear,' MONTH ', nmonth,' DAY ', nday   &
              ,'Julian day : ', zjulian

         ! II.3 Define the T grid trend file (nidvor)
         ! ---------------------------------
         CALL dia_nam( clhstnam, ntrd, 'vort' )                  ! filename
         IF(lwp) WRITE(numout,*) ' Name of NETCDF file ', clhstnam
         CALL histbeg( clhstnam, jpi, glamf, jpj, gphif,1, jpi,   &  ! Horizontal grid : glamt and gphit
            &          1, jpj, 0, zjulian, rdt, nh_t, nidvor)
         CALL wheneq( jpi*jpj, fmask, 1, 1., ndexvor1, ndimvor1 )    ! surface

         ! Declare output fields as netCDF variables
         CALL histdef( nidvor, "sovortPh", cvort//"grad Ph" , "s-2",        & ! grad Ph
            &          jpi,jpj,nh_t,1,1,1,-99,32,clop,zsto,zout)
         CALL histdef( nidvor, "sovortEk", cvort//"Energy", "s-2",          & ! Energy
            &          jpi,jpj,nh_t,1,1,1,-99,32,clop,zsto,zout)
         CALL histdef( nidvor, "sovozeta", cvort//"rel vorticity", "s-2",   & ! rel vorticity
            &          jpi,jpj,nh_t,1,1,1,-99,32,clop,zsto,zout)
         CALL histdef( nidvor, "sovortif", cvort//"coriolis", "s-2",        & ! coriolis
            &          jpi,jpj,nh_t,1,1,1,-99,32,clop,zsto,zout)
         CALL histdef( nidvor, "sovodifl", cvort//"lat diff ", "s-2",       & ! lat diff
            &          jpi,jpj,nh_t,1,1,1,-99,32,clop,zsto,zout)
         CALL histdef( nidvor, "sovoadvv", cvort//"vert adv", "s-2",        & ! vert adv
            &          jpi,jpj,nh_t,1,1,1,-99,32,clop,zsto,zout)
         CALL histdef( nidvor, "sovodifv", cvort//"vert diff" , "s-2",      & ! vert diff
            &          jpi,jpj,nh_t,1,1,1,-99,32,clop,zsto,zout)
         CALL histdef( nidvor, "sovortPs", cvort//"grad Ps", "s-2",         & ! grad Ps
            &          jpi,jpj,nh_t,1,1,1,-99,32,clop,zsto,zout)
         CALL histdef( nidvor, "sovortbv", cvort//"Beta V", "s-2",          & ! beta.V
            &          jpi,jpj,nh_t,1,1,1,-99,32,clop,zsto,zout)
         CALL histdef( nidvor, "sovowind", cvort//"wind stress", "s-2",     & ! wind stress
            &          jpi,jpj,nh_t,1,1,1,-99,32,clop,zsto,zout)
         CALL histdef( nidvor, "sovobfri", cvort//"bottom friction", "s-2", & ! bottom friction
            &          jpi,jpj,nh_t,1,1,1,-99,32,clop,zsto,zout)
         CALL histdef( nidvor, "1st_mbre", cvort//"1st mbre", "s-2",        & ! First membre
            &          jpi,jpj,nh_t,1,1,1,-99,32,clop,zsto,zout)
         CALL histdef( nidvor, "sovorgap", cvort//"gap", "s-2",             & ! gap between 1st and 2 nd mbre
            &          jpi,jpj,nh_t,1,1,1,-99,32,clop,zsto,zout)
         CALL histend( nidvor )

      ENDIF