[ncl-talk] fatal:Variable (plot) is undefined

[grace]

Hi all:
    I am trying to plot precipitation with wrfout data and try to add .shp on the plot.it says fatal:Variable (plot) is undefined  .My NCL version is 6.2.0.
    How can I slove those problem?
        This is my script:
 ;   Example script to produce plots for a WRF real-data run,
;   with the ARW coordinate dynamics option.
 load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl" 
begin
;
; The WRF ARW input file.  
; This needs to have a ".nc" appended, so just do it.
  a = addfile("/public/home/huanglei/wrfdata/5km/wrfout_d03_2015-08-02_12:00:00.nc","r")
 ; We generate plots, but what kind do we prefer?
 ; type = "x11"
 type = "pdf"
; type = "ps"
; type = "ncgm"
  wks = gsn_open_wks(type,"plt_Precip_5km0802")
 
; Set some basic resources
  res = True
  res at MainTitle = "REAL-TIME WRF"
   mpres  = True  ; Map resources
  mpres at mpOutlineOn = False  ; Turn off map outlines
  mpres at mpFillOn    = False  ; Turn off map fill
  mpres at mpGridAndLimbOn = True
 ;res at mpProjection          = "Lambert"
  pltres = True ; Plot resources
  pltres at PanelPlot  = True   ; Tells wrf_map_overlays not to remove overlays
 
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; What times and how many time steps are in the data set?
  FirstTime = True
  times = wrf_user_getvar(a,"times",-1)  ; get all times in the file
  ntimes = dimsizes(times)         ; number of times in the file
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   do it = 0,24,3            ; TIME LOOP
     print("Working on time: " + times(it) )
    if (FirstTime) then            ; Save some times for tracking tendencies
      times_sav = times(it)
    end if
    res at TimeLabel = times(it)   ; Set Valid time to use on plots
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; First get the variables we will need        
 
  ; Get non-convective, convective and total precipitation of 5km                          
    rain_exp = wrf_user_getvar(a,"RAINNC",it)
    rain_con = wrf_user_getvar(a,"RAINC",it)
    rain_tot = rain_exp + rain_con
    rain_tot at description = "Total Precipitation"
 
 ;calculate the precipitation 
    if( FirstTime ) then
      if ( it .eq. 0 ) then
        rain_exp_save = rain_exp
        rain_con_save = rain_con
        rain_tot_save = rain_tot
       else
        rain_exp_save = wrf_user_getvar(a,"RAINNC",it-1)
        rain_con_save = wrf_user_getvar(a,"RAINC",it-1)
        rain_tot_save = rain_exp_save + rain_con_save
 
        FirstTime = False
        times_sav = times(it-1)
      end if
    end if
     rain_tot_tend = rain_tot - rain_tot_save
     rain_tot_tend at description = "Precipitation of 5km"
   ; Bookkeeping, just to allow the tendency at the next time step
    rain_exp_save = rain_exp
    rain_con_save = rain_con
    rain_tot_save = rain_tot
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
     if( .not. FirstTime ) then     ; We will skip the first time
       ; Plotting options for Precipitation
        opts_r = res                        
        opts_r at UnitLabel            = "mm"
        opts_r at cnLevelSelectionMode = "ExplicitLevels"
        opts_r at cnLevels             = (/ .1, .2, .4, .8, 1.6, 3.2, 6.4, \
                                        12.8, 25.6, 51.2, 102.4/)
        opts_r at cnFillColors         = (/"White","White","DarkOliveGreen1", \
                                        "DarkOliveGreen3","Chartreuse", \
                                        "Chartreuse3","Green","ForestGreen", \
                                        "Yellow","Orange","Red","Violet"/)
        opts_r at cnInfoLabelOn        = False
        opts_r at cnConstFLabelOn      = False
        opts_r at cnFillOn             = True
    
        opts_r at gsnDraw      =  False                  
        opts_r at gsnFrame     =  False
    
      ; Precipitation Tendencies 
        opts_r at SubFieldTitle = "from " + times_sav + " to " + times(it)
    
        contour_tend = wrf_contour(a,wks, rain_tot_tend,opts_r) ; total (color)
         delete(opts_r)
  
       ; MAKE PLOTS                                       
         plot = wrf_map_overlays(a,wks,contour_tend,pltres,mpres)
 
    end if    ; END IF FOR SKIPPING FIRST TIME
 ;>============================================================<
;                      add China map
;>------------------------------------------------------------<
      
  shp_name1    = "/public/home/huanglei/map/diquJie_polyline.shp"
   lnres                  = True
  lnres at gsLineColor      = "gray25"
  lnres at gsLineThicknessF = 0.5   
  id = gsn_add_shapefile_polylines(wks,plot,shp_name1,lnres)
 ; shp_name2    = "/home/huanglei/map/China/cnmap/cnhimap.shp"
 ;  prres=True
 ; prres at gsLineThicknessF = 2.0       
;  prres at gsLineColor = "black"
 ; plotcn3 = gsn_add_shapefile_polylines(wks,plot,shp_name2,prres)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
     times_sav = times(it)
    FirstTime = False
 draw(plot)       ; This will draw the map and the shapefile outlines.
  frame(wks)
  end do        ; END OF TIME LOOP
 end
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20151103/9dc264b4/attachment.html