;=======================================================================
; name:
;   xy.ncl
;
; purpose:
;   to plot lon-lat map
;
; author:
;   m.yoshimori
;=======================================================================

begin

; specify years
  year0 = 1979  ; start year of the dataset
  syear = 1991  ; start year of the analysis
  eyear = 2020  ; end year of the analysis

; specify file names
  fin = "./GPCP/precip.mon.mean.nc"  ; input file name (netCDF)
  fout = "./out/xy_pr"               ; output file name (png/eps etc.)

; get data
  in = addfile(fin,"r")  ; open a file
  tmp = in->precip       ; read the data
  printVarSummary(tmp)   ; check the data

; annual means from "syear" to "eyear"
  y1 = (syear - year0)*12
  y2 = (eyear - year0 + 1)*12 - 1
  yyyymm = yyyymm_time(syear, eyear, "integer")
  tmp2 = month_to_annual_weighted(yyyymm, tmp(y1:y2,:,:), 1)
  delete(tmp)

; long-term average
  var = dim_avg_n_Wrap(tmp2, 0)
  delete(tmp2)

;-----
; plot
;-----

  wks = gsn_open_wks("png",fout)           ; open a png/eps file
  gsn_define_colormap(wks,"precip_11lev")  ; choose a color map

; basic settings
  res = True		; plot mods desired
  res@gsnDraw = True	; draw plot
  res@gsnFrame = True	; advance frame
  res@cnFillOn = True	; turn on color fill
  res@cnLinesOn = False	; turn off contour lines
  res@cnLineLabelsOn = False    ; turn off contour labels

; contour levels
  res@cnLevelSelectionMode = "ManualLevels"
  res@cnMinLevelValF =  1.0
  res@cnMaxLevelValF =  12.0
  res@cnLevelSpacingF = 1.0

; adjust aspect ratio
  res@mpShapeMode = "FreeAspect"
  res@vpWidthF = 0.80
  res@vpHeightF = 0.45

; map
  res@mpFillOn = False         ; turn off gray continents
  res@mpCenterLonF = 180       ; set centers the plot at 180
  res@gsnMajorLonSpacing = 60  ; tick mark interval for longitude

; font size
  res@tiMainFontHeightF = 0.022     ; fontsize of the main title
  res@txFontHeightF = 0.02          ; fontsize of the subtitles
  res@tmXBLabelFontHeightF = 0.018  ; fontsize of tickmark labels (x-axis)
  res@tmYLLabelFontHeightF = 0.018  ; fontsize of tickmark labels (x-axis)

; titles
  res@tiMainString = "ERA5 1991-2020 annual mean climatology"  ; title
  res@gsnCenterString = ""                                     ; subtitle
  res@gsnLeftString = "Precipitation"                          ; upper-left subtitle
  res@gsnRightString = ""                                      ; upper-right subtitle

; subtitle attributes
;  res@txFontHeightF    = 0.02  ; resize the text
;  res@amOrthogonalPosF = 0.05  ; move text up

; color table
  res@gsnSpreadColors = True  ; spread out color table

; reshape color bar
  res@lbTitleOn          = True
  res@lbOrientation      = "horizontal"
  res@lbBoxEndCapStyle   = "TriangleBothEnds"  ; triangle edges
  res@lbBoxMinorExtentF  = 0.2           ; slim width
  res@lbLabelStride      = 1             ; label interval
  res@pmLabelBarOrthogonalPosF = 0.1   ; shift up&down

; reshape color title
  res@lbTitleString      = "mm/day"
  res@lbTitleFontHeightF = 0.018
  res@lbTitlePosition    = "Right"
  res@lbTitleDirection   = "Across"

; plot
  plot=gsn_csm_contour_map_ce(wks,var,res)

end