[ncl-talk] wavelet period

[Shaimah ali]

Hi,
I am plotting a wavelet based on this example
https://www.ncl.ucar.edu/Applications/Scripts/wavelet_2.ncl.

I need to convert the Y-axis periods in to units of months(like
12,20,40..months),instead of units of years.. So what are the changes i
have to be done in my code.
I have monthly mean data of AOD for 19.7 years.(235 values).
here is my code:

aod = asciiread("aod.dat",-1,"float")
  aod!0 = "time"
  ntime = dimsizes(aod)
  timeo = fspan(2000.19,2019.,ntime)
  aod&time = timeo

  time  = timeo
  N     = dimsizes(time)

;WAVELET

  mother  = 0
  param   = 6.0
  dt      = 0.25   ;timesteps in units of years
  s0      = dt
  dj      = 0.25
  jtot    = 1+floattointeger(((log10(N*dt/s0))/dj)/log10(2.))
  npad    = N
  nadof   = 0
  noise   = 1
  siglvl  = .05
  isigtest= 0

  w =
wavelet(aod,mother,dt,param,s0,dj,jtot,npad,noise,isigtest,siglvl,nadof)

; create coodinate arrays for plot

  power            = onedtond(w at power,(/jtot,N/))
  power!0          = "period"                        ; Y axis
  power&period     = w at period                      ; convert period to
units of years

  power!1          = "time"                          ; X axis
  power&time       = time

  power at long_name  = "Power Spectrum"
  power at units      = "1/unit-freq"


; compute significance ( >= 1 is significant)
  SIG              = power                            ; transfer meta data
  SIG              = power/conform (power,w at signif,0)
  SIG at long_name    = "Significance"
  SIG at units        = " "

; initial resource settings

  wks = gsn_open_wks("png","01")             ; send graphics to PNG file

  res                     = True                  ; plot mods desired
  res at gsnDraw             = True ;False                 ; Do not draw plot
  res at gsnFrame            = True ;False                 ; Do not advance
frome
  res at gsnMaximize         = True
  res at cnFillOn            = True                  ; turn on color
  res at cnFillPalette       = "BlAqGrYeOrReVi200"   ; set color map
  res at cnFillMode          = "RasterFill"          ; turn on raster mode
  res at cnRasterSmoothingOn = True                  ; turn on raster smoothing
  res at cnLinesOn           = False ;True                 ; turn off contour
lines
  res at cnLineLabelsOn      = False
  res at cnInfoLabelOn       = False
  res at trYReverse          = False  ;True                  ; reverse y-axis
  res at tmLabelAutoStride   = False   ;True
  res at tmYROn              = False
  res at tmXTOn              = False

  res at tmYLMode = "Explicit"

  res at tmYLValues = (/1,2,4,8,16,32,64,128/)
  res at tmYLLabels = (/"1","2","4","8","16","32","64","128"/)

  res at tmXBMode = "Explicit"
  res at tmXBValues = (/20,40,60,80,100,120,140,160,180,200,220,240/)
  res at tmXBLabels =
(/"20","40","60","80","100","120","140","160","180","200","220","240"/)


  res at cnLevelSelectionMode = "ExplicitLevels"       ; set manual contour
levels
  res at cnLevels =
(/0.01,0.02,0.04,0.08,0.1,0.12,0.14,0.16,0.20,0.24,0.28,0.32/)

  res at tiMainString       = ""
  res at gsnRightString      = ""
  res at gsnCenterString     = "AOD"
  res at gsnLeftString       = ""
  res at tiYAxisString       = "Periodicities (years)"
  res at tiXAxisString       = "Months(2000-2019)"

  plot = new(2,graphic)
  plot(0) = gsn_csm_contour(wks,power,res)


THANK YOU
Shaima.N
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