GEMPAK Manual |
Programs
DCHRCN
DCHRCN decodes forecast/advisory reports for tropical depressions,
tropical storms and hurricanes for the Atlantic and Pacific Oceans
from a real-time data feed, or from a file fed to the program
through standard input, and writes the data to an ASCII file. The
program is controlled by inputs to the command line.
The inputs are program options and the output file name or template.
For example, for real-time data feeds:
dchrcn [options] output_file
If running the program interactively with standard input, the -c
option must be used. The input file must also be specified.
For example:
dchrcn -c YYMMDD/HHNN [other_options] output_file < input_file
A template may be used to specify the output file name. The file
name template uses the date and time of the bulletin or report
to replace the following characters.
YYYY or YY Year with or without the century
MM Month number
DD Day
HH Hour
NN Minute
The format of the output ASCII file (with the 2 '|' lines given
below appearing as one line in the file) is as follows:
|Type|Valid_time|Name|Advisory_Number|Position_accuracy
|Direction|Speed|Minimum_Central_Press|Corr_flag
Lat Lon Type
Quadrant data
Where: Type is TD (tropical depression), TS (tropical storm),
HU (hurricane) or HUT (typhoon). If type is not 'HUT',
an 'E' or 'S' is appended for an extratropical or
subtropical storm, respectively
Valid_time is the full GEMPAK date/time string
Name is the storm name
Advisory_number is the number assigned to the storm
Position_accuracy is how close the center of the eye
is to the given latitude and longitude
Direction is the direction that the storm is moving toward
Speed is the speed of the storm in knots
Minimum_Central_Press is the pressure value in mb in the eye
at the valid time
Corr_flag is a flag indicating a correction (0 or 1)
Extra spaces may appear anywhere in this line of information,
except in the first character position. The first character must
be a bar (|).
The current and forecast latitude and longitude values and storm
type are read using the FORTRAN format (2F9.2,4X,A).
Quadrant data (current 100 kt or 64 kt, 50 kt, and 34 kt winds and
12 ft seas, and forecast 100 kt or 64 kt, 50 kt and 34 kt winds)
are read using the FORTRAN format (4X,A).
Prior to June 1, 2004, reports from the Joint Typhoon Warning
Center (JTWC) included 100 kt winds instead of 64 kt winds. As of
June 1, 2004, the JTWC reports 64 kt winds, as do the TPC and CPHC.
In the decoded quadrant sections, the first wind position,
originally labelled as '64', is now labelled as 'MW', the maximum
wind, where 'MW' represents either the 64 kt winds from any report
or the 100 kt winds from Western Pacific (JTWC) reports issued
before June 1, 2004. If the storm type is 'HUT' and the date is
prior to June 1, 2004, the first quadrant data is assumed to be the
100 kt wind information.