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"
begin

  fname = "tst.txt"

  n_col = numAsciiCol(fname)
  n_var = n_col
  n_pt  = numAsciiRow(fname)
  dataf  = asciiread(fname,(/n_pt,n_var/),"float")
  
;---read longitude
  lon = dataf (:,0)
  
;---read latitude
  lat = dataf (:,1)
  
;---read data for presence of convective cloud
  storm = dataf (:,2)
  
;---define the workstation (plot type and name)
  wks = gsn_open_wks("png","plot_field")
  
;--set resources
  wks = gsn_open_wks("x11","ce")
  res                     = True
  res@gsnMaximize         = True
  
  res@mpDataBaseVersion   = "MediumRes"   ;-- map resolution
  res@mpMinLonF           = min(lon)
  res@mpMaxLonF           = max(lon)
  res@mpMinLatF           = min(lat)
  res@mpMaxLatF           = max(lat)

  res@sfXArray            = lon
  res@sfYArray            = lat
  
  res@cnFillOn            = True        ; Turn on contour fill.
  res@cnLinesOn           = False       ; Turn off contour lines

;-- create the contour map plot
;  plot = gsn_csm_contour_map(wks,storm,res)         ; create a default plot
  contour = gsn_csm_contour_map(wks,storm,res)

end