Global Cyclone Climatology Data Details

There are three data files for each of the two levels (1000 mb and 500 mb). All are plain text. One file (centers.dat) contains the individual cyclone centers for each grid as determined by the automated method. The second file, tracks.dat, contains cyclone tracks. The third file, latlon2.dat, contains the latitude and longitude coordinates of each grid point. These are described in detail below.

There are two directories at the ftp site, one for each level. They are completely self-contained; i.e., if you are only interested in one of the two levels you don't need anything from the other directory. The latitude-longitude file is the same in both directories; the read program (described below) is the same except for the number of cyclones specified for each level. The two largest data files are compressed with gzip.

The centers.dat File

The text file centers.dat contains the following information for each grid (12-hourly):

The cyclone id is simply a long integer starting with the first cyclone found on the first grid (id=0) and ending with the last cyclone on the last grid. The actual longitudes and latitudes are obtained by using the indices in this file with the longitude and latitude arrays from the file latlon2.dat (see below). For example, if the longitude index for a particular cyclone is 9, it's longitude is the 10th value in the longitude array (indices start at 0).

The tracks.dat File

The tracks.dat file contains the cyclone start/end dates and ids for each track. The first line has the total number of tracks. Each of the subsequent lines corresponds to one track and consists of:

Only tracks that have more than two cyclones in them were written to tracks.dat. These values can be cross-referenced with the data read in centers.dat.

The latlon2.dat File

The latlon2.dat file contains the latitudes and longitudes of the analysis grid. There are 73 latitudes (degrees), ranging from +90 (North Pole) to -90 (South Pole) in 2.5 degree increments. The latitude values are followed by 72 longitudes (degrees), ranging from 0 to 360 eastward from the Prime Meridian, in 5 degree increments.


The only program provided (at present) is for reading the data files. It is called and is written in the IDL language (Interactive Data Language, Research Systems, Inc.). Conversion to other languages should be straightforward.

Additional IDL programs can be provided upon request. However, these would be provided with no guarantee. Additionally, little, if any, support for them should be expected.

Go to the FTP site