;----------------------------------------------------------------------
; This script overlays vectors over color contours over a map.
;
; 
;----------------------------------------------------------------------

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"


begin
;---Make a list of all files we are interested in
  DATADir = "~/ncl/data/20160115-18/"
  FILES = systemfunc (" ls -1 " + DATADir + "rap* ")
  numFILES = dimsizes(FILES)
  do ifil = 0,numFILES-1
;---Start the graphics
  wks = gsn_open_wks("png","jan16storm")
  a = addfile(FILES(ifil)+".grb2","r") ; Open the next file
  refc = a->REFC_P0_L200_GLC0
  u    = a->UGRD_P0_L7_GLC0
  v    = a->VGRD_P0_L7_GLC0

  lat = a->gridlat_0
  lon = a->gridlat_0

;---Set some contour resources
  cnres                   = True

  cnres@gsnMaximize       = True     ; maximize plot in frame
  cnres@gsnDraw           = False    ; turn off draw
  cnres@gsnFrame          = False    ; turn off frame

  cnres@cnFillOn          = True     ; turn on color fill
  cnres@cnFillPalette     = "gui_default" ; choose colormap
  cnres@cnLinesOn         = False    ; turn off contour lines
  
  cnres@gsnLeftString     = "REFC ("  + refc@units + ")"
  cnres@gsnRightString    = "UV winds ("  + u@units + ")"

  cnres@cnLevelSelectionMode = "ManualLevels"        ; set manual contour levels
  cnres@cnMinLevelValF       =  -12.                 ; set min contour level
  cnres@cnMaxLevelValF       =   36                  ; set max contour level
  cnres@cnLevelSpacingF      =   4                   ; set contour spacing

  cnres@mpOutlineOn       = False    ; We're going to add 
  cnres@mpFillOn          = False    ; shapefile outlines.

  cnres@mpMinLatF         =   35
  cnres@mpMaxLatF         =   47
  cnres@mpMinLonF         =  -80
  cnres@mpMaxLonF         =  -67

  
  
  contour_plot = gsn_csm_contour_map(wks,refc,cnres)

;---Set some vector resources
  vcres                   = True

  vcres@gsnMaximize       = True     ; maximize plot in frame
  vcres@gsnDraw           = False    ; turn off draw
  vcres@gsnFrame          = False    ; turn off frame

  vcres@vcMinDistanceF    = 0.005    ; thin the vectors
  vcres@vcRefLengthF      = 0.05     ; width/num_vectors (~25 vectors)

  vcres@vcLineArrowColor  = "Gray25"

  vcres@gsnRightString    = ""       ; turn off sub-titles
  vcres@gsnLeftString     = ""

  vector_plot = gsn_csm_vector(wks,u,v,vcres)

  overlay(contour_plot,vector_plot)


  frame(wks)
  end do
end