;----------------------------------------------------------------------
; This is a basic NCL template for creating contours over maps.
;
; Use "contour_template.ncl" if you don't need to put the
; contours over a map.
;----------------------------------------------------------------------

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"

begin
;---Read data
  a   = addfile("file.nc","r")
  x   = a->x

  lat = a->lat      ; Only necessary if "x" doesn't
  lon = a->lon      ; contain 1D coordinate arrays.

;---Open workstation and change color map
  wks = gsn_open_wks("x11","contour_map")   ; "ps", "pdf", "png"
  gsn_define_colormap(wks,"amwg")

;---Set some resources
  res                   = True

  res@gsnMaximize       = True     ; maximize plot in frame

;---These are sample resources you might want to set
  res@cnFillOn          = True     ; turn on contour fill

  res@cnLinesOn         = False    ; turn off contour lines
  res@cnLineLabelsOn    = False    ; turn off line labels

;---Use if you have a high-res grid that could be slow to plot.
; res@cnFillMode        = "RasterFill"

;---This can also speed things up
; res@trGridType        = "TriangularMesh

;---These two resources are not needed in V6.1.0
  res@gsnSpreadColors   = True     ; span full color map
  res@lbLabelAutoStride = True     ; nice spacing for labelbar labels

;---Uncomment if you want to change the contour levels
;  mnmxint = nice_mnmxintvl( min(x), max(x), 18, False)
;  res@cnLevelSelectionMode = "ManualLevels"
;  res@cnMinLevelValF       = mnmxint(0)
;  res@cnMaxLevelValF       = mnmxint(1)
;  res@cnLevelSpacingF      = mnmxint(2)

  res@tiMainString      = "This is a main title"

;---Set to False if plotting regional data or setting sfXArray/sfYArray
  res@gsnAddCyclic      = True

  res@sfXArray          = lon   ; Only necessary if x doesn't 
  res@sfYArray          = lat   ; contain 1D coordinate arrays
;
; Zoom in on map if desired. There are other ways to zoom in on
; map if you have a different projection, like lambert conformal.
;
  res@mpMinLatF         = min(lat)
  res@mpMaxLatF         = max(lat)
  res@mpMinLonF         = min(lon)
  res@mpMaxLonF         = max(lon)
  res@mpCenterLonF      = (res@mpMinLonF + res@mpMaxLonF) / 2.

  plot = gsn_csm_contour_map(wks,x,res)
end