DKRZ NCL Germany sunshine duration colored by temperature

Example script:

;---------------------------------------------------------------
; DKRZ NCL Example:  sunshine_duration_colored_by_temperature.ncl
;
; Description: draw yearly sunshine duration hours and
;      color it with temperature
;
; NCL version:    requires version > 6.5.0 to use elseif
;
; 24.07.18 kmf
;---------------------------------------------------------------
; Procedure to attach a labelbar.
;---------------------------------------------------------------
undef("add_labelbar")
procedure add_labelbar(wks,plot,colors,labels,position)
local vph, vpw, vpx, vpy, nboxes, lbres, lbid, amres, annoid
begin

  getvalues plot
     "vpHeightF" : vph
     "vpWidthF" : vpw
     "vpXF" : vpx
     "vpYF" : vpy
  end getvalues

  nboxes = dimsizes(colors)

  lbres = True ;-- labelbar only resources
  lbres@lbAutoManage = False ;-- necessary to control sizes
  if(position .eq. "vertical") then
     lbres@vpWidthF = 0.15 * vpw ;-- labelbar width
     lbres@vpHeightF = 0.95 * vph ;-- labelbar height
     lbres@lbOrientation = "Vertical"
  elseif(position .eq. "horizontal") then
     lbres@vpWidthF = vpw ;-- labelbar width
     lbres@vpHeightF = 0.08 ;-- labelbar height
     lbres@lbOrientation = "Horizontal"
  end if
  lbres@lbFillColors = colors ;-- labelbar colors
  lbres@lbMonoFillPattern = True ;-- solid fill pattern
  lbres@lbLabelFontHeightF = 0.016 ;-- label size
  lbres@lbLabelAlignment = "InteriorEdges" ;-- center of box
  lbres@lbPerimOn = False

  lbid = gsn_create_labelbar(wks,nboxes,labels,lbres)

  amres = True
  amres@amJust = "CenterLeft"
  if(position .eq. "horizontal") then
     amres@amParallelPosF = -0.5
     amres@amOrthogonalPosF = 0.78
  elseif(position .eq. "vertical") then
     amres@amParallelPosF = 0.52
     amres@amOrthogonalPosF = 0.0
  end if

  plot@annoid = gsn_add_annotation(plot,lbid,amres)

end

;---------------------
; MAIN
;---------------------
begin
  file1 = "$HOME/data/DWD/annual_sunshine_duration_regional_averages_sd_year.txt"
  file2 = "$HOME/data/DWD/annual_air_temperature_mean_regional_averages_tm_year.txt"

  delim = ";"

  ;-- read sunshine duration data
  data1 = asciiread(file1,-1,"string")
  year1 = toint(str_get_field(data1(2:),1,delim))
  sdur = tofloat(str_get_field(data1(2:),19,delim))
  sdur@units = "h"
  nx = dimsizes(year1)

  ;-- read sunshine duration data
  data2 = asciiread(file2,-1,"string")
  year2 = toint(str_get_field(data2(2:),1,delim))
  temp = tofloat(str_get_field(data2(2:),19,delim))
  temp@units = "~S~o~N~C"

  tempmin = min(temp)
  tempmax = max(temp)
  tempstep = fspan(tempmin,tempmax,21)
  nt = dimsizes(tempstep)
  labels = ""+sprintf("%.1f",tempstep)

  print("-----------------------------------")
  print("tempmin: "+tempmin)
  print("tempmax: "+tempmax)
  print("-----------------------------------")

  start_year = year1(0)
  y1ind = ind(year2 .eq. start_year)
  print("Starting year: "+year2(y1ind))

  ;-- read color map and assign color index array
  cmap = read_colormap_file("cmp_b2r")
  cmap := cmap(20::2,:)
  ncols = dimsizes(cmap(:,0))
  colors = new(nx,integer)

  ;-- generate the color index for each bar
  do i=0,nx-1
     if(ismissing(temp(i))) then
        colors(i) = -1
     else
        do j=0,dimsizes(tempstep)-1
           if (temp(i) .lt. tempstep(0)) then
               colors(i) = 0
           elseif (temp(i) .ge. tempstep(dimsizes(tempstep)-1)) then
               colors(i) = nx
           elseif (temp(i) .ge. tempstep(j) .and. temp(i) .lt. tempstep(j+1)) then
               colors(i) = j+1
           end if
        end do
     end if
  end do

  ;-- open workstation
  wks = gsn_open_wks("png","plot_sunshine_duration")

  ;-- set resources
  res = True
  res@gsnDraw = False
  res@gsnFrame = False

  res@vpXF = 0.12
  res@vpYF = 0.8
  res@vpWidthF = 0.8
  res@vpHeightF = 0.4

  res@trXMinF = min(year1)-1 ;-- adds space on either end
  res@trXMaxF = max(year1)+1 ;-- of the 1st and last bars
  res@trYMinF = min(sdur)-10. ;-- adds space on either end
  res@trYMaxF = max(sdur)+10. ;-- of the 1st and last bars

  res@gsnXYBarChart = True ;-- turn on bar chart
  res@gsnXYBarChartBarWidth = 0.75 ;-- change bar widths
  res@gsnXYBarChartColors = cmap(colors,:)

  res@tmXBLabelFontHeightF = 0.012
  res@tmXBLabelFontHeightF = 0.012

  res@tiXAxisString = "Years" ;-- x-axis title string
  res@tiYAxisString = "Sunshine duration ["+sdur@units+"]" ;-- y-axis title string
  res@tiXAxisFontHeightF = 0.014
  res@tiYAxisFontHeightF = 0.014

  ;-- create the plot
  plot = gsn_csm_xy(wks,year1,sdur,res)

  ;-- add labelbar
  add_labelbar(wks,plot,cmap,labels,"horizontal")

  ;-- add title strings
  title1 = "Germany: Sunshine duration hours per year"
  title2 = "(colored by the average temperature per year)"
  title3 = "Sunshine duration: min ="+sprintf("%8.2f",min(sdur))+" max ="+sprintf("%8.2f",max(sdur))+" ["+sdur@units+"]"
  title4 = "Temperature: min ="+sprintf("%8.2f",min(temp))+" max ="+sprintf("%8.2f",max(temp))+" ["+temp@units+"]"

  txres = True
  txres@txFontHeightF = 0.018
  gsn_text_ndc(wks,title1,0.5,0.95,txres)
  txres@txFontHeightF = 0.014
  gsn_text_ndc(wks,title2,0.5,0.92,txres)
  txres@txJust = "CenterLeft"
  txres@txFont = 29
  txres@txFontHeightF = 0.009
  gsn_text_ndc(wks,title3,res@vpXF,0.86,txres)
  txres@txFontHeightF = 0.009
  gsn_text_ndc(wks,title4,res@vpXF,0.84,txres)

  ;-- draw the plot and advance the frame
  draw(plot)
  frame(wks)

end

Result: