;****************************************************
; Concepts illustrated:
;   - Drawing an XY plot with two different Y axes
;   - Changing the title on the Y axis
;   - Changing the line dash pattern in an XY plot
;   - Changing the line color for multiple curves in an XY plot
;   - Setting the mininum/maximum value of the Y axis in an XY plot
;
;****************************************************
;
; These files are loaded by default in NCL V6.2.0 and newer
; load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"   
; load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"   
;****************************************************
begin
;***************************
; read in data
;***************************
  A    = addfile("HPRF_1951_2017_JJAS_fldmean.nc","r")
  B    = addfile("HPTmean_1951_2017_JJAS_fldmean.nc","r")
  C    = addfile("HPTmin_1951_2017_JJAS_fldmean.nc","r")
  D    = addfile("HPTmax_1951_2017_JJAS_fldmean.nc","r")   ; read in left variable (y1)
  
  rf    = A->rf
  tmean = B->t
  tmin  = C->t
  tmax  = D->t          ; read in right variable (y2)
  tmean_time = B->time                ; this is our x
  rf_time = A->time

  Tdata=new((/3,dimsizes(tmean!time)/),float)
  Tdata(0,:)=tmin(0,:,:)
  Tdata(1,:)=tmean(0,:,:)
  Tdata(2,:)=tmax(0,:,:)

;***************************
;---Convert to fractional years for easier plotting.
;***************************
Tdata_yfrac = cd_calendar(tmean_time,4)
rf_yfrac    = cd_calendar(rf_time,4)

;***************************
;---LOOKING AT THE DATA!
;***************************
printVarSummary(tmean)
printVarSummary(tmin)
printVarSummary(tmax)
printVarSummary(rf)
printMinMax(tmean,0)
printMinMax(tmin,0)
printMinMax(tmax,0)
printMinMax(rf,0)

printVarSummary(tmean_time)
printVarSummary(rf_time)
printMinMax(tmean_time,0)
printMinMax(rf_time,0)

printVarSummary(Tdata_yfrac)
printVarSummary(rf_yfrac)
printMinMax(Tdata_yfrac,0)
printMinMax(rf_yfrac,0)

;***************************
; plot parameters
;***************************
  wks = gsn_open_wks("png","xy")                    ; send graphics to PNG file 

; resources for "left" variable
  resL                        = True 
  resL@xyLineThicknesses      = 2.                  ; thicker line
  resL@tiYAxisString = "Temperature in Deg. Celsius"  ; axis string
  resL@xyLineColors      = "red"  

; resources for "right" variable
  resR                        = True                      
  resR@xyDashPatterns         = 1                 ; dashed line for 2nd
  resR@xyLineThicknesses      = 2                 ; thicker line
  resR@tiYAxisString = "Rainfall in mm"   ; axis string
  resR@xyLineColors      = "blue" 


  plot = gsn_csm_x2y2(wks,Tdata_yfrac,rf_yfrac,Tdata,rf,resL,resR)
  end