a=addfile("WesternAgroClimRegion_MonthlySum_1901_2017Jan.nc","r")
b=a->rf
aveg=dim_avg_n(b,0)
stdev=dim_stddev_n(b,0)
;stdev = where(stdev.ne.0,stdev,stdev@_FillValue)
cv=(stdev/aveg)*100

;*****************************************
;create plot
;*****************************************
  wks  = gsn_open_wks("png","CV_map")   ; send graphics to PNG file
  res                     = True          ; plot mods desired
  res@cnFillOn            = True          ; turn on color
  res@cnLinesOn           = False 
  res@cnFillMode          = "RasterFill"       ; Raster Mode
  res@cnFillPalette       = "gui_default" ; set color map
  ;res@vpWidthF           = 0.5          ; change aspect ratio of plot
  ;res@vpHeightF          = 0.3
  res@gsnMaximize         = False          ; maximize plot size
  ;res@gsnDraw            = False
  ;res@gsnFrame           = False
  plot = gsn_csm_contour(wks,cv,res)       ; contour the variable
  frame(wks)
  ;end