[ncl-talk] ttest values not plotting

[Sri Nandini]

Hello

I am trying to plot ttest values overlay onto the T2m differences, but it is not being plotted nor shaded region according to 95%confidence limits with ttest.
Below is the script, i would be grateful if someone could let me know of my omission or deletion in the resources plotting attributes.

;Use NCL's named dimensions to reorder in time.
;Calculate the temporal means and variances using the dim_avg and dim_variance functions.
;Specify a critical significance level to test the lag-one auto-correlation coefficient and determine the (temporal) number of equivalent sample sizes in each grid point using equiv_sample_size.
;Specify a critical significance level for the ttest and test if the means are different at each grid point. 
; This file still has to be loaded manually
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl"

 yrStrt = 0000
 yrLast = 0100
; ==============================================================
; Open the file: Read only the user specified period 
; ==============================================================
f= addfile("T2M_C.nc", "r") ;Model Control
TIME   = f->time
  YYYY   = cd_calendar(TIME,-1)/100                 ; entire file
  iYYYY  = ind(YYYY.ge.yrStrt .and. YYYY.le.yrLast)
T41    = f->TREFHT(iYYYY,:,:)
printVarSummary(T41)                                ; (time, lat,lon)
T4    = lonFlip(T41)
printVarSummary(T4)                                ; (time, lat,lon)
T4 at _FillValue = -9.96921e+36  
aveX = dim_avg_n_Wrap(T4, 0)                   ;; average over the 0th dim
printVarSummary(aveX)                                ; (lat,lon) 
varX = dim_variance_n_Wrap(T4,0)               ; compute variance
printVarSummary(varX)                                ; (lat,lon) 
;==============================================================================

f2= addfile("T2M_CC.nc", "r") ;Current Caspian
TIME2  = f2->time
  YYYY2   = cd_calendar(TIME2,-1)/100                 ; entire file
  iYYYY2  = ind(YYYY2.ge.yrStrt .and. YYYY2.le.yrLast)
air22   = f2->TREFHT(iYYYY2,:,:)
air2    = lonFlip(air22)
printVarSummary(air2)                                ; (time, lat,lon)
air2 at _FillValue = -9.96921e+36                              
aveY = dim_avg_n_Wrap(air2,0)  ; average over the 0th dim
printVarSummary(aveY)                                ; (lat,lon) 
varY = dim_variance_n_Wrap(air2,0) ; compute variance
printVarSummary(varY)                                ; (lat,lon) 
;================================================================================
;Use "ttest" to compute the probabilities
;=================================================================================

  sigr = 0.05                        ; critical sig lvl for r

 xEqv = new(dimsizes(varY),typeof(varY),varY at _FillValue)
printVarSummary(xEqv)                               ; (lat,lon) 
  xEqv = equiv_sample_size (T4(lat|:,lon|:,time|:), sigr,0)   
 copy_VarMeta(varY,xEqv)
printVarSummary(xEqv)                               ; (lat,lon) 

 yEqv = new(dimsizes(varY),typeof(varY),varY at _FillValue)
printVarSummary(yEqv)                                ; (lat,lon) 
  yEqv = equiv_sample_size (air2(lat|:,lon|:,time|:), sigr,0)
copy_VarMeta(varY,yEqv)
printVarSummary(yEqv)                                ; (lat,lon) 
                   
;==================================================================================
 probt = new(dimsizes(varY),typeof(varY),varY at _FillValue)

 probt = ttest(aveY,varY,xEqv,aveX,varX,yEqv,True,False) ; values are between 0 and 1

;probt = 100.*(1. -ttest(aveY,varY,xEqv,aveX,varX,yEqv,True,False)) ; all areas whose value > 95 are significant
printVarSummary(probt)                ; (lat,lon) 
copy_VarMeta(varY,probt)
printVarSummary(probt)                ; (lat,lon) 
print(probt)                   ;check to make sure values are between 0 and 1.
;============================================================
;calculate the T2M difference 
;============================================================ 
 T2diff = new(dimsizes(aveY),typeof(aveY),aveY at _FillValue)
printVarSummary(T2diff)                                 
copy_VarMeta(aveY,T2diff)
printVarSummary(T2diff)                                 
T2diff=aveY-aveX
   printVarSummary(T2diff)                                ; (lat,lon) 
;====================================================================
;Here is a section of my code that draws a color fill plot, and then
;overlays contours of statistical significance.
;====================================================================
   wks = gsn_open_wks("pdf","T2M_ttest")
   gsn_define_colormap(wks,"BlWhRe")

  res = True
  res at cnFillOn             = True                ; turn on color
  res at gsnSpreadColors      = True                ; use full colormap

  res at cnLinesOn            = False               ; turn off contour lines
  res at cnLevelSelectionMode = "ManualLevels"  ; set manual contour levels
  res at cnMinLevelValF       = -2.             ; set min contour level
  res at cnMaxLevelValF       =  2.             ; set max contour level
  res at cnLevelSpacingF      =  0.2            ; set contour spacing

  res at gsnDraw              = False           ; Do not draw plot
  res at gsnFrame             = False           ; Do not advance frome

  res at tiMainString         = "T2M Difference: 50yrs overlay with ttest"
  res at gsnCenterString      = "5% stippled"
  res at gsnLeftString        = "K"

   res at cnRasterModeOn              = True              ; Raster mode shows grid cells
   plot = gsn_csm_contour_map_ce(wks,T2diff,res)  
   plot = ZeroNegDashLineContour (plot)

  res2 = True                            ; res2 probability plots
  res2 at gsnDraw             = False       ; Do not draw plot
  res2 at gsnFrame            = False       ; Do not advance frome
  res2 at cnLevelSelectionMode = "ExplicitLevels" ; set explicit cnlev
  ;res2 at cnLevels   = (/.95/)    ; only have 1 contour level
  ;res2 at cnFillPatterns = (/-1,17/) ; don't fill <0.95, stipple >=0.95
  res at cnFillOn = False

  res2 at cnInfoLabelOn       = False
  res2 at cnLinesOn           = False       ; do not draw contour lines
  res2 at cnLineLabelsOn      = False       ; do not draw contour labels
  res2 at cnFillScaleF        = 0.6         ; add extra density

  plot2 = gsn_csm_contour(wks,probt,res2)                                     ; add cyclic point

  opt = True                    ; set up parameters for pattern fill
  opt at gsnShadeFillType = "pattern"  ; specify pattern fill
  opt at gsnShadeLow      = 17         ; stipple pattern
  plot2   = gsn_contour_shade(plot2, 0.091, 3., opt) ; stipple all areas < 0.09 contour
  overlay (plot, plot2)

  draw (plot)
  frame(wks)

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