;*************************************************
; a default black and white plot with the default
; ncl labeling. All neg contour lines are dashed
; and the zero line is made to be double thickness.
;************************************************
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"   
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"    
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl"
load "$HAO_NCL_LIB/halfzp2full.ncl"
;************************************************
begin
;************************************************
; before the data can be plotted, there is a 
; sequence of things that have to be done to it:
;************************************************
  in    = addfile("/chewy/d/murphys/files/pyrj001.nc","r")                
  x     = in->UN
  x     = halfzp("UN",x)                     ; convert to full zp


  t2plt   = 2                                ; time index to plot
  lat2plt = 56                               ; lat value to plot
;************************************************
; create plot
;************************************************
  wks = gsn_open_wks("ps" ,"zplon")           ; open a ps file

  res                          = True         ; plot mods desired
  res@cnLineLabelPlacementMode = "constant"   ; best line label mode
  res@tiMainString             = "Default Black and White Plot"
  res@gsnDraw                  = False        ; don't draw yet
  res@gsnFrame                 = False        ; don't advance frame yet

  plot = gsn_csm_contour(wks,x(t2plt,:,{lat2plt},:), res)
  plot = ZeroNegDashLineContour(plot)
  draw(plot)
  frame(wks)
end