load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"  
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"  
begin
  a = addfile("$NCARG_ROOT/lib/ncarg/data/cdf/uv300.nc","r")
  ujan = a->U(0,:,:)                              ; read January zonal winds
  ujul = a->U(1,:,:)                              ; read July zonal winds

  wtype          = "png"
  wtype@wkWidth  = 1700
  wtype@wkHeight = 1700
  wks = gsn_open_wks(wtype,"ce")                  ; open a ps file

  res                     = True
  res@gsnDraw             = False
  res@gsnFrame            = False
  res@gsnMaximize         = True

  res@gsnRightString      = ""
  res@gsnLeftString       = ""
  res@cnInfoLabelOn       = False
  res@cnLineLabelsOn      = False

  res@cnLineColor         = "NavyBlue"
  map_plot = gsn_csm_contour_map(wks,ujan,res)

  res@cnLineColor         = "ForestGreen"
  jul_plot = gsn_csm_contour(wks,ujul,res)

  overlay(map_plot,jul_plot)
  draw(map_plot)
  frame(wks)

;---Close the png and trim the white space from the image
  delete(wks)
  system("convert -trim ce.png ce_trimmed.png")
end