load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
 load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
 load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
 load "$NCARG_ROOT/lib/ncarg/nclscripts/contrib/ut_string.ncl"
begin
;---Open WRF output file
    a= addfile("/home/gaurav/ncl_scripts/sst2014mslp.nc","r")

;---Read several WRF variables at first time step
  it  = 210
  slp = wrf_user_getvar(a,"msl",it)   ; sea level pressure
  ;wrf_smooth_2d( slp,3 )             ; smooth slp
  
;---Now get the lowest (bottommost) level
  nl  = 0
  
;---Change the metadata
    wks = gsn_open_wks("png","SLP")

;---Set common resources for all plots
  res                = True
  res@gsnFrame       = True
  res@gsnDraw        = True
  res@gsnLeftString  = ""
  res@gsnRightString = ""

;---Necessary for contours to be overlaid correctly on WRF projection
  res@tfDoNDCOverlay = True
   

;---SLP line contour plot
  levels      = ispan(960,1010,4)
  info_string = "Sea level pressure contours from 960 to 1020 by 4"
  
  slp_res                                = res
  slp_res@cnLineColor                    = "NavyBlue"
  ;slp_res@cnLevelSelectionMode           = "ExplicitLevels"
  ;slp_res@cnLevelSelectionMode           = "ImplicitLevels"
  ;slp_res@cnLevels                       = levels
  slp_res@cnLineLabelBackgroundColor     = -1    ; transparent
  slp_res@cnLineThicknessF               = 2
  slp_res@cnHighLabelsOn                 = False
  slp_res@cnLowLabelsOn                  = True
  slp_res@cnHighLabelBackgroundColor     = -1
  slp_res@cnLowLabelBackgroundColor      = -1
  slp_res@cnInfoLabelString              = info_string
  slp_res@cnInfoLabelFontColor           = "NavyBlue"
  slp_res@cnInfoLabelPerimOn             = True

  contour_psl = gsn_csm_contour(wks,slp,slp_res)


;---Map plot
  minLon=50
  maxLon=95
  minLat=0
  maxLat=30
  map_res               = True
  map_res@mpMinLonF     = minLon
  map_res@mpMaxLonF     = maxLon
  map_res@mpMinLatF     = minLat
  map_res@mpMaxLatF     = maxLat
  map_res@gsnFrame      = True
  map_res@gsnDraw       = True
  map_res@tiMainString  = a
  map_res@gsnLeftString = slp@description + " (" + slp@units + ")~C~" 
  map_res@gsnLeftStringFontHeightF = 0.02
  

;---Set map resources based on projection on WRF output file
  map_res = wrf_map_resources(a,map_res)

  map = gsn_csm_map(wks,map_res)

;---Overlay plots on map and draw.
    overlay(map,contour_psl)
  
  draw(map)   ; This will draw all overlaid plots and the map
  frame(wks)
end