begin

; specify file names (input&output, netCDF)
  pathin = ""                  ; directory
  fin1 = "File1.nc"  ; input file name #1
  fin2 = "File2.nc"  ; input file name #2
  ;fout = "signif_eraint_t2m_DJF"      ; output file name
  ;foutnc = fout+".nc"

; open input files
  in1 = addfile(pathin+fin1,"r")
  in2 = addfile(pathin+fin2,"r")

; read data
  tmp1 = in1->rf
  tmp2 = in2->rf

; t-test
  xtmp = tmp1(lat|:,lon|:,time|:)
  ytmp = tmp2(lat|:,lon|:,time|:)
  ;xtmp = tmp1(latitude|:,longitude|:,time|:)
  ;ytmp = tmp2(latitude|:,longitude|:,time|:)
  Xave = dim_avg_Wrap(xtmp)
  Yave = dim_avg_Wrap(ytmp)
  Xvar = dim_variance(xtmp)
  Yvar = dim_variance(ytmp)
  Xs   = dimsizes(tmp1(0,0,:))
  Ys   = dimsizes(tmp2(0,0,:))
  iflag    = False  ; population variance similar
  tval_opt = False  ; p-value only
  prob = ttest(Xave,Xvar,Xs,Yave,Yvar,Ys,iflag,tval_opt)
  pval = (/prob/)
;  diff@long_name = "difference of the means"
  pval@long_name = "probability"
;-----
; plot
;-----

printVarSummary(pval)

; judge significance
  siglvl = 0.05
;  sig = pval
  ndim = dimsizes(pval)
  nlat = ndim(0)
  nlon = ndim(1)
;  do j=0,nlat-1
;    do i=0,nlon-1
;      if (.not.ismissing(pval(j,i))) then
;         if (pval(j,i).lt.siglvl) then
;            sig(j,i) = 1.
;         else
;            sig(j,i) = 0.
;         end if
;       end if
;;    end do
;  end do

  sig = pval   ; preallocate array w/metadata
  sig = where(pval.lt.siglvl,1,0)
;*********************************
  wks = gsn_open_wks("x11","test")
  res                      = True		; significance
  res@gsnDraw              = False		; draw plot
  res@gsnFrame             = False		; advance frome
  res@cnInfoLabelOn        = False		; turn off info label
  res@cnLinesOn            = False		; draw contour lines
  res@cnLineLabelsOn       = False		; draw contour labels
;  res@cnFillScaleF         = 0.6		; add extra density
  res@cnFillDotSizeF       = 0.003

; activate if gray shading for B&W plot
  res@cnFillOn = True
  res@cnFillMode = "RasterFill"
;  res@cnFillColors = (/"transparent","transparent"/)	; choose one color for our single cn level
  res@cnLevelSelectionMode = "ExplicitLevels"	; set explicit contour levels
  res@cnLevels = 0.5	; only set one level
  res@lbLabelBarOn = False

  res@tiMainString = ""     ; title
  res@gsnCenterString = ""  ; subtitle
  res@gsnLeftString = ""    ; upper-left subtitle
  res@gsnRightString = ""   ; upper-right subtitle

  plot = gsn_csm_contour(wks,sig,res)

  draw(plot)
  frame(wks)
end