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

begin
  x = fspan(0.,100.,51)                    ; generate dummy data
  y = sin(x*6.28/50.)

  wks = gsn_open_wks ("ncgm", "bar" )      ; open workstation

  res                          = True
  res@gsnMaximize              = True      ; maximize plot on page
  res@gsnXYBarChart            = True      ; turn on bar charts
  res@gsnXYBarChartOutlineOnly = True      ; draw outlines only

  plot = gsn_csm_xy (wks,x,y,res)          ; draw first plot

  delete(res@gsnXYBarChartOutlineOnly)

  res@gsnYRefLine           = 0            ; reference line
  res@gsnAboveYRefLineColor = "red"        ; above ref line fill red
  res@gsnBelowYRefLineColor = "blue"       ; below ref line fill blue

  plot = gsn_csm_xy (wks,x,y,res)          ; draw second plot
end