a=addfile("WesternAgroClimRegion_MonthlySum_1901_2017Jan.nc","r")
b=a->rf
rfavg=dim_avg(b)
rfstddev=dim_stddev(b)
cv= (rfavg/rfstddev)*100
;*****************************************
;create plot
;*****************************************
  wks  = gsn_open_wks("png","conwomap")   ; send graphics to PNG file

  res                     = True          ; plot mods desired

  res@cnFillOn            = True          ; turn on color
  res@cnFillPalette       = "gui_default" ; set color map
 
  res@vpWidthF            = 0.5           ; change aspect ratio of plot
  res@vpHeightF           = 0.3

  res@gsnMaximize         = True          ; maximize plot size

  plot = gsn_csm_contour(wks,cv,res)       ; contour the variable