4.5 trackinfo storm track management module

The trackinfo module is somewhat different from those listed above in that it is not a stand-alone executable script. Instead, this python module should be run interactively by the user from the python command line (for more information, see www.python.org here). The most common use of this module is in the plotting of hurricane tracks from the NHC Best Track archive. The trackinfo module, can be used to produce the necessary input files for the func_drawTracks.f90 function of the NCAR_Utilities SPA module, which in turn generates track maps and track overlays.

To invoke the python shell, type python at the prompt. Once the python prompt appears, you will need to load the trackinfo module by entering:

     from trackinfo import *

(For python gurus, a full listing of the classes available in the trackinfo module can be written by using import trackinfo and print trackinfo.__doc__ instead of the above). A list of the methods available to you from the trackinfo module can be obtained by entering the command:

     print TrackList.__doc__

The first step is to initialize a new TrackList object by entering the command:

     nhcBestTrack = TrackList('path/to/nhc/best/track','nhc')

The new object (nhcBestTrack - whatever you decide to call it - is now filled with all of the best track information from the NHC best track datafile (available at the NHC website www.nhc.noaa.gov here). There are now a number of methods that you can apply to get useful information from the tracking dictionary. For example, you can create and list a subset of the 2001 hurricanes:

     print TrackList.SubList.__doc__  #get info on the SubList interface
     storms2001 = nhcBestTrack.SubList({'year':'2001'})
     storms2001.PrintInfo({},'name:year:category')

This information can then be written directly to the format used by the SPA track plotting subprogram func_drawTracks.f90 using a write method:

     storms2001.WriteList('path/to/output/file')

This generates an SPA-compatible ASCII output file containing preformatted entries of all storms in the 2001 instance of the TrackList object. This file simply needs to be provided to the appropriate plotting function in the SPA.

Another potentially-useful feature of the trackinfo module is its ability to quickly identify storm locations. For example, to get a subset of the storms that have impacted the northwest coast of Florida, you can run something like:

     FLstorms = nhcBestTrack.InBox([28,30],[83,84])
     FLstorms.PrintInfo({},'name:year')

The attributes available to the user are:

• trackEntry – full tracking information string.
• name – name of the tropical cyclone.
• year – year of occurence of the tropical cyclone.
• month – month (numeric) of occurence of the tropical cyclone.
• day – tropical cyclone start day.
• longMonth – full month (string) of occurence of the tropical cyclone.
• shortMonth – abbreviated month (string) of occurence of the tropical cyclone.
• intensity – a list of intensity indicators for each reporting time.
• location – a list of location indicators for each reporting time.
• category – the category of maximum intensity for the storm.

Furthermore, a class variable namedOnly is defined for the TrackList class, which allows the user to control the reporting of information prior to the advent of NHC naming. The default pseudological value is 1 (off - no reporting of pre-naming storms); however, this is easily changed upon request:

     TrackList.namedOnly = 0

Note that this value is immediately redefined for all instances of the TrackList class, and that none of the constructors need to be rerun.