Last updated 03-Jul-07
Extensive evaluation of tropical cyclone characteristics, motion, and forecast errors is often performed at the Joint Typhoon Warning Center (JTWC), Fleet Numerical Oceanography Center (FNOC), the Naval Research Laboratory (NRL) and elsewhere. This work has shown the need for a uniform tropical cyclone data base. A flat-file database meeting this requirement was developed for the Automated Tropical Cyclone Forecast System (ATCF). Within ATCF, this database provides uniform data for the individual applications requiring tropical cyclone data. ATCF applications work with the flat-file database, making any modifications to the data there. At the end of a year, the flat-file database is copied, compressed in an archive directory. Procedures within ATCF can recall and modify data from the archive data without modifying the archive itself.
The data base covers five tropical cyclone basins. The length and amount of data coverage varies between basins and is listed below along with the definitions of the basins themselves (Table 1).
Table 1: Area and Data Coverage for Storm Basins.
Basin |
Latitude Span |
Longitude Span |
Track Data |
History Data |
Forecast Data |
Fix Data |
Wind Data |
WP
|
EQ-60N |
100-180E |
1945-? |
1967-76 1978-? |
1967-76 1978-? |
1966-77 1979-? |
1989-? |
IO |
EQ-60N |
40-100E |
1945-? |
1978-? |
1978-? |
1972-? |
1989-? |
EP |
EQ-60N |
140W-80W |
1949-80 1989-? |
1989-? |
1989-? |
1989-? |
1989-? |
CP |
EQ-60N |
180W-140W |
1949-80 1989-? |
1989-? |
1989-? |
1989-? |
1992-? |
AL |
EQ-60N |
100W-0W |
1945-? |
1992-? |
|
1992-? |
|
SH |
EQ-60S |
20E-120W |
1980-? |
1980-? |
1980-? |
1980-? |
1989-? |
(Notes: Question marks indicate data updated yearly. Southern Hemisphere storm years are July 1 - June 30. For example, the first tropical cyclone after June 30, 1982 would be the first storm of the 1983 storm year).
The tropical cyclone data comes from a variety of sources. Best track data for the Southern Hemisphere 1945-79, for the Indian Ocean 1945-77, and for the Western Pacific 1945-66 were obtained from the Consolidated World-Wide Tropical Cyclone Data Base, National Climatic Data Center, Asheville, NC. Best track data for the Eastern Pacific, Central Pacific and the Atlantic are from the National Hurricane Center. The remaining data was extracted from the Joint Typhoon Warning Center (JTWC) Tropical Cyclone Data.
The tropical cyclone description data is stored in ascii files. Each storm is given a unique eight character code called the storm ID to identify it in the database. The storm ID is of the format RECYYYYY, where
RE = Region (basin) of Origin
AL - North Atlantic
WP - Western North Pacific
CP - Central North Pacific
EP - Eastern North Pacific
IO - North Indian Ocean
SH - Southern Hemisphere
LS - Southern Atlantic
CY = Annual Cyclone Number(01-99)
YYYY = Year
For example, WP011992 is the first (01) western North Pacific (WP) storm in 1992 (1992).
It should also be noted that while there is a best track for every storm with forecast and fix data, the reverse is not true. There are five types of data for tropical cyclones which are discussed in the remainder of this section.
In the ATCF, tropical cyclone data are stored in flat files and are accessed via executables or scripts. The $ATCFSTRMS directory on ATCF contains data files for active storms; the $ATCFARCHIVES directory contains data for all storms. This section outlines flat file data formats for each of the file types in the ATCF database.
4.1 DESCRIPTIVE DATA
These data include storm name, basin of origin, sub-basin of origin, storm number, year of origin, track type, beginning date, ending date, number of basins entered, storm state (e.g., warning or archive), and the specific basins entered.
Note: Track type is a subjective classification of the storm as a straight mover, recurver, or odd mover. A straight storm path is one which maintained a somewhat constant heading between 250o - 360o. A storm is considered a recurver if it turned from an initial path toward the west or northwest to a path toward the northeast. An odd moving storm, therefore, is one which did not fit in the other two categories or contained loops in the track. ).
Each storm has one descriptive record which is a brief summary of the storm history including storm name, track type, maximum development level, etc. The information is stored in the file storms.txt for all active storms, and storms.archive for all storms for a selected year.
4.2 BEST TRACK
These data are the 6-hourly storm positions based on a post-storm, subjectively smoothed path. In some cases, the data obtained was in 12 hour increments. For these storms, 6-hourly positions were interpolated using the method of Akima (1970). The best tracks files are named b<stormid>.dat. For example, bwp132000.dat contains best track positions for the 13th storm of the 2000 western north pacific season.
4.3 STORM HISTORY
These data are the real-time storm positions, intensity, and structure of the storm. The data are used for warning generation (00Z, 06Z, 12Z, and 18Z), to generate synthetic observations for global and mesoscale models (COMS), and to initiate objective aid forecasts (CARQ). ( Fig 3 ). Lines beginning with 01CARQ and 02WRNG are storm history lines. The forecasts are in files are named a<stormid>.dat. For example, awp132000.dat contains forecasts for the 13th storm of the 2000 western north pacific season.
4.4 FORECASTS
These data contain the objective forecasts, and the official forecast. Lines without CARQ, WRNG, or COMS are forecasts. Each date-time group may contain one or both types of data. A description of the various objective forecasts may be found in the techlist.dat file on ATCF, which is updated frequently. published by JTWC.
Tropical cyclone wind radii forecasts and observations are included in these data. Specifically, the forecasts are for 64, 50 and 34 kt winds. Prior to 1990, 30 knot wind radii were forecast in the western North Pacific Ocean, the Indian Ocean, and the Southern Hemisphere. There are also cases with 100 kt wind radii prior to 2000. Here is an example of the naming convention: awp132000.dat contains forecasts for the 13th storm of the 2000 western north pacific season.
4.5 FIXES
Tropical cyclone fixes from five different platforms (radar, satellite, aircraft, scatterometer, and synoptic fixes taken from weather charts) are contained in the data base. The files are named f<stormid>.dat. For example, fwp132000.dat is the fix file for the 13th storm of the 2000 western north pacific season.
ATCF produces a few different ascii files for use by other systems. Among these are the official warning, the warning summary (a shorthand version of the official warning), the "tcw" file (a file containing the warning summary, followed by the official warning, followed by the best track), and the Navy OVERLAY/2 or "JOTS" file (this is another representation of the warning as a set of graphical instructions - pen up, pen down, etc.). The files all have names similar to other ATCF files. The naming convention is <stormid>.xxx, where xxx is the file type (xxx=wrn for warnings, xxx=sum for warning summaries, xxx=tcw for tcw files, and xxx=jts for JOTS files). For example, wp132000.wrn is the warning text for the 13th storm of the 2000 western north pacific season.
The following are formats and examples for this growing list of output files: