;*****************************************************
; cru_6.ncl
;
; Concepts illustrated:
;   - Plotting CRU (Climate Research Unit) data
;   - Drawing filled bars above and below a given reference line
;   - Adding text and lines                                     
;   - Paneling three plots vertically on a page
;   - Changing the width and height of a plot
;   - Attaching several plots                   
;
;*****************************************************
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"  
;*****************************************************

  f    = addfile("Tave_18562003.nc","r")

  year = f->year
  
  tnh  = f->TAveNhAn                             ; tnh(:) 
  tsh  = f->TAveShAn
  tgl  = f->TAveGlAn

;***************************************
; Some weights for 'decadal' filter (smoother)
; Other weights could be used
;***************************************  
  wgts = (/ 1,6,19,42,71,96,106,96,71,42,19,6,1 /)*1.0
  wgts = wgts/sum(wgts)

  TNH  = wgt_runave_n_Wrap(tnh, wgts, 1, 0)      ; reflective end pts 
  TSH  = wgt_runave_n_Wrap(tsh, wgts, 1, 0)  
  TGL  = wgt_runave_n_Wrap(tgl, wgts, 1, 0)  

;***************************************
; create plot
;***************************************  
  wks = gsn_open_wks("ps","cru")                  ; open ps file
  plot= new (3,graphic)                           ; create graphical array

  res                      = True                 ; plot mods desired
  res@gsnDraw              = False                ; don't draw yet      
  res@gsnFrame             = False                ; don't advance frame yet

  res@vpHeightF             = 0.43                ; Changes the aspect ratio
  res@vpWidthF              = 0.90                ; of plots

  res@trYMinF               = -0.75               ; min value on y-axis
  res@trYMaxF               =  0.75               ; max value on y-axis

  res@trXMinF               = 1855                ; min value on x-axis
  res@trXMaxF               = 2005                ; max value on x-axis

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

  res@gsnXYBarChart         = True                ; create bar chart 
  res@xyLineColors          = (/"red","blue"/)    ; line around bar color

; text and line resources

  txres               =  True
  txres@txFontHeightF = 0.02
  txres@txJust        = "CenterLeft"
  txres@txFontThicknessF = 2.0      ; default=1.00
  txres@txFontHeightF    = 0.025    ; default=0.05


  plres               =  True
  plres@gsLineColor   = "black"                   ; color of lines
  plres@gsLineThicknessF = 3.0                    ; thickness of lines

; create plots; force no default long_name and units labeling via (/ ... /)

  plot(0)  = gsn_csm_xy (wks,year, (/ tnh /),res)
  text_tnh = gsn_add_text(wks,plot(0),"Northern Hemisphere", 1870, 0.75*res@trYMaxF ,txres)
  curv_tnh = gsn_add_polyline(wks,plot(0),year, TNH ,plres)

  res@tiYAxisString         = "HadCRUT3: Anomalies (C)"
  plot(1) = gsn_csm_xy (wks,year, (/ tsh /),res)
  text_tsh = gsn_add_text(wks,plot(1),"Southern Hemisphere", 1870, 0.75*res@trYMaxF ,txres)
  curv_tsh = gsn_add_polyline(wks,plot(1),year, TSH ,plres)
  delete(res@tiYAxisString)

  plot(2) = gsn_csm_xy (wks,year, (/ tgl /),res)
  text_tgl = gsn_add_text(wks,plot(2),"Globe", 1870, 0.75*res@trYMaxF ,txres)
  curv_tgl = gsn_add_polyline(wks,plot(2),year, TGL ,plres)

; create panel plot

  resP              = True                         ; panel mods desired
  resP@gsnMaximize  = True
  gsn_panel(wks,plot,(/3,1/),resP)

;********************************************
; create attached plots
;********************************************

; Set up resource lists for attaching the plot.
; The res1 will apply to the base plot, and the
; res2 to the plots being attached.  These resources
; lists are *not* for changing things like line color,
; but for changing things like whether the plots
; are maximized, and which axis they are attached on.
;
  res1                     = True
  res2                     = True
  res2@gsnAttachPlotsXAxis = True

; plot(0) will  be the base plot.

  amid = gsn_attach_plots(plot(0),(/plot(1), plot(2)/),res1,res2)

  draw(plot)    
  frame(wks)