Re: drawing fronts

Thank you. I followed your instructions and it works now.

Avel

Subject: Re: drawing fronts
From: haley@ucar.edu
Date: Thu, 30 Jun 2011 12:46:13 -0600
CC: ncl-talk@ucar.edu
To: avel.o@hotmail.com

Avel,
I have to admit to not understanding the wmxxxx routines very well, but I'm pretty sure that you have to call them *after* you've already drawn the map. This is because the internal code needs to have an existing map in order to draw the weather fronts on it.
This is untested, but please try this:
          pltres@PanelPlot = True ; tell wrf_map_overlays not to remove all the overlaid plots.

          opts_z@ContourParameters = (/ 60.0 /)
          contour_height = wrf_contour(a,wks, z_plane,opts_z)
          plot = wrf_map_overlays(a,wks,(/contour_height, \
                                    vector/),pltres,mpres) draw(plot) ; this is necessary, b/c PanelPlot=True turns off gsnDraw.
 ; Draw a stationary front.
  wmsetp("ezf",1) ; Tell wmap we are using an existing map projection.
  wmsetp("lin",1.0) ; Line width of front curve.
  wmsetp("fro","stationnary"); Specify stationary front.
  wmsetp("cfc",4) ; Use blue for the triangles.
  wmsetp("wfc",2) ; Use red for the bumps.
  wmsetp("swi",0.02) ; Increase the size of the bumps and triangles.
  xxlat = (/50., 55.0/) ; Latitudes.
  xxlon = (/-5., 15./) ; Longitudes.
  wmdrft(wks, xxlat, xxlon)
     frame(wks)

--Mary
On Jun 30, 2011, at 7:34 AM, Avel O wrote:Hello,

I try to overlay weather fronts on some wrf output fields. To make a small test, I defined the front as:

  xxlat = (/50., 55.0/) ; Latitudes.
  xxlon = (/-5., 15./) ; Longitudes.

but the front doesn't seem to be located correctly. Some help would be appreciated. Thanks in advance.

PS: Here's the full script:

; Example script to produce plots for a WRF real-data run,
; with the ARW coordinate dynamics option.
; Interpolating to specified pressure levels

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

begin
;
; The WRF ARW input file.
; This needs to have a ".nc" appended, so just do it.
  a = addfile("./wrfout_d01_2008-08-03_12:30:00.nc","r")

; We generate plots, but what kind do we prefer?
; type = "x11"
; type = "pdf"
 type = "ps"
; type = "ncgm"
  wks = gsn_open_wks(type,"fronts")

; Set some Basic Plot options
  res = True
  res@MainTitle = "REAL-TIME WRF"
  res@Footer = False

  pltres = True
  mpres = True
  mpres@mpGeophysicalLineColor = "Black"
  mpres@mpNationalLineColor = "Black"
  mpres@mpUSStateLineColor = "Black"
  mpres@mpGridLineColor = "Black"
  mpres@mpLimbLineColor = "Black"
  mpres@mpPerimLineColor = "Black"
  mpres@mpGeophysicalLineThicknessF = 2.0
  mpres@mpGridLineThicknessF = 2.0
  mpres@mpLimbLineThicknessF = 2.0
  mpres@mpNationalLineThicknessF = 2.0
  mpres@mpUSStateLineThicknessF = 2.0

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; What times and how many time steps are in the data set?
  times = wrf_user_list_times(a) ; get times in the file
  ntimes = dimsizes(times) ; number of times in the file

; The specific pressure levels that we want the data interpolated to.
  pressure_levels = (/ 500./) ; pressure levels to plot
  nlevels = dimsizes(pressure_levels) ; number of pressure levels

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

  it = 0 ; TIME LOOP

    res@TimeLabel = times(it) ; Set Valid time to use on plots

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; First get the variables we will need

    tc = wrf_user_getvar(a,"tc",it) ; T in C
    u = wrf_user_getvar(a,"ua",it) ; u averaged to mass points
    v = wrf_user_getvar(a,"va",it) ; v averaged to mass points
    p = wrf_user_getvar(a, "pressure",it) ; pressure is our vertical coordinate
    z = wrf_user_getvar(a, "z",it) ; grid point height
    rh = wrf_user_getvar(a,"rh",it) ; relative humidity

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

    do level = 0,nlevels-1 ; LOOP OVER LEVELS

      pressure = pressure_levels(level)

      z_plane = wrf_user_intrp3d( z,p,"h",pressure,0.,False)
      u_plane = wrf_user_intrp3d( u,p,"h",pressure,0.,False)
      v_plane = wrf_user_intrp3d( v,p,"h",pressure,0.,False)

      spd = (u_plane*u_plane + v_plane*v_plane)^(0.5) ; m/sec
      spd@description = "Wind Speed"
      spd@units = "m/s"
      u_plane = u_plane*1.94386 ; kts
      v_plane = v_plane*1.94386 ; kts
      u_plane@units = "kts"
      v_plane@units = "kts"

      ; Plotting options for Wind Speed
        opts = res
        opts@cnLineColor = "MediumSeaGreen"
        opts@ContourParameters = (/ 10. /)
        opts@cnInfoLabelOrthogonalPosF = 0.07 ; offset second label information
        opts@gsnContourLineThicknessesScale = 3.0
        contour_spd = wrf_contour(a,wks,spd,opts)
        delete(opts)

      ; Plotting options for Wind Vectors
        opts = res
        opts@FieldTitle = "Wind" ; overwrite Field Title
        opts@NumVectors = 47 ; wind barb density
        vector = wrf_vector(a,wks,u_plane,v_plane,opts)
        delete(opts)

      ; Plotting options for Geopotential Heigh
        opts_z = res
        opts_z@cnLineColor = "Black"
        opts_z@gsnContourLineThicknessesScale = 1.0

      ; MAKE PLOTS

; Draw a stationary front.

  wmsetp("ezf",1) ; Tell wmap we are using an existing map projection.
  wmsetp("lin",1.0) ; Line width of front curve.
  wmsetp("fro","stationnary"); Specify stationary front.
  wmsetp("cfc",4) ; Use blue for the triangles.
  wmsetp("wfc",2) ; Use red for the bumps.
  wmsetp("swi",0.02) ; Increase the size of the bumps and triangles.
  xxlat = (/50., 55.0/) ; Latitudes.
  xxlon = (/-5., 15./) ; Longitudes.
  wmdrft(wks, xxlat, xxlon)

          opts_z@ContourParameters = (/ 60.0 /)
          contour_height = wrf_contour(a,wks, z_plane,opts_z)
          plot = wrf_map_overlays(a,wks,(/contour_height, \
                                    vector/),pltres,mpres)
        delete(opts_z)

    end do ; END OF LEVEL LOOP

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

end

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Received on Sat Jul 2 15:15:23 2011