Graphics: NCL – Example

Example to show how to generate a cyclone track plot. This example shows the track plots for Hurricane Katrina.

The script you will need is called CreateTracks.ncl
Note: This script a a large number of command line options, depending on the type of plot you want to create. Please refer to the top of this script for a full list of options.

At this time the script can read data generated with RIP4, or the tracking data generated when running WRFV3 with vortex following option.
For this example we going to use the data WRF generates when running with the vortex following option.
 

After you have run WRF (with vortex following option ON), do the following (this will get all the tracking data written out during the model run).
Or download this file if you don't want to run the model first.

grep ATCF rsl.out.0000 >> kat_track

Note: You can use any filename to place the tracking data in.
 

Run the tracking script to create the plot below (left):

ncl CreateTracks.ncl 'inputFILE="kat_track"' 'stormNAME="Katrina"' 'wksTYPE="x11"'

Notes:
1. The format is very important, to take care to give the right quotes as above.
2. You must supply the inputFILE name you places the data in.
3. The storm name is only used on the header of the plot and is optional.
4. The default output time is a pdf file, in this case, we want the plot to display on our screen.

 Run the tracking program again - this time adding a best track (see plot one right below):

ncl CreateTracks.ncl 'inputFILE="at_track"' 'stormNAME="Katrina"' 'wksTYPE="x11"' bestTRACK=True 'btFILE="BestTrack.Katrina"' lonMIN=-92.0 lonMAX=-74.0

Notes:
1. bestTRACK=True, switch this option ON.
2. btFILE, points to the best track data. NOTE, the file format of this file. For this example, download the best track data from here before running this script.
3. The best track is normally plotted as a red line, with btCOLOR you can change this to any color you like.
4. The best track data for this plot may be slightly outside the domain (the domain is automatically determined by the track input data), so we in this case we manually increase the domain size.