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Overlays multiple plots, created from other ARW WRF plot functions.


load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"      ; These two libraries are automatically
load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"    ; loaded from NCL V6.4.0 onward.
                                                              ; No need for user to explicitly load.

	function wrf_overlays (
		nc_file   : file,     
		wks       : graphic,  
		plots [*] : graphic,  
		res   [1] : logical   



Reference to an input netCDF file opened with addfile.


An NCL Workstation identifier. The identifier is one returned either from calling gsn_open_wks or calling create to create a Workstation object.


Plots to overlay, possibly created by calls to wrf_contour and/or wrf_vector.


A plot resource list. See the description below.


This function overlays a number of graphical plots, and returns the base plot that contains all the overlaid plots. This is typically used for idealized ARW WRF model runs.

Some special resources are recognized for the res resource list:

  • NoTitles (default: False)

    If set to True, then the top left titles will not be drawn. The main titles will be left alone.

    This resource can be useful if you are planning to panel the plots.

  • CommonTitle (default: True)

    If set to False, then the top field titles will not be drawn.

  • FramePlot (default: True)

    If set to False, then the plot will be drawn, but the frame will not be advanced. This allows you to draw more graphical objects on the same page.

  • PanelPlot (default: False)

    If set to True, then this flags to wrf_map_overlays that these plots are going to be eventually paneled (likely by gsn_panel.) Hence, the plot will not be drawn, nor will the frame be advanced, unless gsnDraw and/or gsnFrame are explicitly set to True.

If you want to use gsn_add_polyxxxx routines (like gsn_add_polymarker) to add primtives to a WRF plot, then you need to set:

plt_res@PanelPlot = True
plt_res@FramePlot = False

before you call wrf_map_overlays. Then, call the appropriate gsn_add_polyxxxx routine to attach the desired primitives, and finally call draw(plot) and frame(wks) to draw the plot with the attached primitives and advance the frame.

wrf_overlays is part of a library of functions and procedures in WRFUserARW.ncl written to help users plot ARW WRF model data. This function replaces wrf_overlay.

See Also

wrf_contour, wrf_vector, wrf_map, wrf_map_overlays


Example 1

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

  ; Open ARW WRF output for the quarter supercell idealized case
  a = addfile("","r")

  wks = gsn_open_wks("x11","test")

  time = 1
  tc2 = wrf_user_getvar(a,"T2",time)   ; T2 in Kelvin
  u10 = wrf_user_getvar(a,"U10",time)  ; u at 10 m
  v10 = wrf_user_getvar(a,"V10",time)  ; v at 10 m

  rest = True
  rest@cnFillOn = True
  contour = wrf_contour(a,wks,tc2,rest)

  resw = True
  vector = wrf_vector(a,wks,u10,v10,resw)

  overid = wrf_overlays(a,wks,(/contour,vector/),True)
You can see some other example scripts and their resultant images at: