NCL Example

Graphics: NCL - Example

Below is a series of basic plots showing how to create a plot for WRF ARW data. The basic plotting techniques shown here can be used for any wrf data file.

wrf_wps_ter1.ncl

In this plot no special WRF functions are used.

A single field is simply read from the file
ter = a->HGT_M(0,:,:)

and plotted
plot = gsn_contour(wks,ter,True)

wrf_wps_ter2.ncl

Add shading to the plot
res = True
res@cnFillOn = True
res@gsnSpreadColors = True
plot = gsn_contour(wks,ter,res)

wrf_wps_ter3.ncl

Change the plot levels
res@cnLevelSelectionMode = "ManualLevels"
res@cnMinLevelValF = 0.
res@cnMaxLevelValF = 1000.
res@cnLevelSpacingF = 50.

wrf_wps_ter4.ncl

Up to now none of the plots had a map background. Adding a map over WRF ARW data is not trivial, so let's rather use some special WRF-NCL scripts to do this.

Make sure to first load the special scripts:
load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"

Create the color fill terrain plot (add a header at the same time):
opts = True
opts@MainTitle = "GEOGRID FIELDS"
res = opts
res@cnFillOn = True ; Create a color fill plot
contour = wrf_contour(a,wks,ter,res)

Overlay plot onto a map (using default plot and map setting):
pltres = True
mpres = True
plot = wrf_map_overlays(a,wks,(/contour/),pltres,mpres)

wrf_wps_ter5.ncl

Change the default plot levels before creating the plot:
res = opts
res@cnFillOn = True ; Create a color fill plot
res@ContourParameters = (/ 0., 1000., 50. /)
contour = wrf_contour(a,wks,ter,res)

wrf_wps_ter6.ncl

Remove initial time and footers from plots:
opts = True
opts@InitTime = False
opts@Footer = False

Change the default map and grid color to Black:
mpres = True
mpres@mpGeophysicalLineColor = "Black"
mpres@mpGridLineColor = "Black"
mpres@mpLimbLineColor = "Black"
mpres@mpNationalLineColor = "Black"
mpres@mpPerimLineColor = "Black"
mpres@mpUSStateLineColor = "Black"


	wrf_wps_ter1.ncl In this plot no special WRF functions are used. A single field is simply read from the file ter = a->HGT_M(0,:,:) and plotted plot = gsn_contour(wks,ter,True)

	wrf_wps_ter2.ncl Add shading to the plot res = True res@cnFillOn = True res@gsnSpreadColors = True plot = gsn_contour(wks,ter,res)

	wrf_wps_ter3.ncl Change the plot levels res@cnLevelSelectionMode = "ManualLevels" res@cnMinLevelValF = 0. res@cnMaxLevelValF = 1000. res@cnLevelSpacingF = 50.

	wrf_wps_ter4.ncl Up to now none of the plots had a map background. Adding a map over WRF ARW data is not trivial, so let's rather use some special WRF-NCL scripts to do this. Make sure to first load the special scripts: load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl" Create the color fill terrain plot (add a header at the same time): opts = True opts@MainTitle = "GEOGRID FIELDS" res = opts res@cnFillOn = True ; Create a color fill plot contour = wrf_contour(a,wks,ter,res) Overlay plot onto a map (using default plot and map setting): pltres = True mpres = True plot = wrf_map_overlays(a,wks,(/contour/),pltres,mpres)

	wrf_wps_ter5.ncl Change the default plot levels before creating the plot: res = opts res@cnFillOn = True ; Create a color fill plot res@ContourParameters = (/ 0., 1000., 50. /) contour = wrf_contour(a,wks,ter,res)

	wrf_wps_ter6.ncl Remove initial time and footers from plots: opts = True opts@InitTime = False opts@Footer = False Change the default map and grid color to Black: mpres = True mpres@mpGeophysicalLineColor = "Black" mpres@mpGridLineColor = "Black" mpres@mpLimbLineColor = "Black" mpres@mpNationalLineColor = "Black" mpres@mpPerimLineColor = "Black" mpres@mpUSStateLineColor = "Black"