Explanation of Digital eTRaP Formats

NOAA/NESDIS has made the eTRaP output available to users via anonymous ftp for five days in three formats: McIDAS area file, text file and gif file. McIDAS users can easily display the data while users of the text format can develop the means to view the data on their own systems.

Current text files, McIDAS area files and gif files can be accessed through the following site: http://satepsanone.nesdis.noaa.gov/pub/TRAP/ETRAP/

The text file will have the following format where east longitudes are positive and west longitudes are negative:

Line 1: BB##YYYY MMDDHH StormName

• BB - Basin
  • AL - Atlantic
  • EP - East Pacific
  • CP - Central Pacific
  • WP - Northwest Pacific
  • NI - North Indian (includes Bay of Bengal and Arabian Sea)
  • EI - Southeast Indian (between 90 deg E and 130 deg E)
  • WI - Southwest Indian (west of 90 deg E)
  • NT - Northern Territory (between 130E and 142 deg E)
  • SW - Southwest Pacific (between 142E and 160 deg E)
  • SE - Southeast Pacific (east of 160E)
• ## Storm number taken from forecast bulletin for systems in East Pacific, Atlantic and Central Pacific; otherwise 99 in all other ocean basins
• YYYY - The calendar year the storm occurred
• MMDDHH - Current month day and forecast hour
• StormName - The name of the storm

Line 2: GGLON SSLON LONL LONR GGLAT SSLAT LATL LATR

• GGLON - The number of grid points in the longitudinal direction
• SSLON - The resolution (in degrees) of the rainfall grid in the longitudinal direction
• LONL - The longitude of the lower left hand corner of the rainfall grid
• LONR - The longitude of the upper right hand corner of the rainfall grid
• GGLAT - The number of grid points in the latitudinal direction
• SSLAT - The resolution (in degrees) of the rainfall grid in the latitudinal direction
• LATL - The latitude of the lower left hand corner of the rainfall grid
• LATR - The latitude of the upper right hand corner of the rainfall grid

Line 3-7: LON LAT TIME

• Since the eTRaP is generated from multiple forecasts, the LON and LAT will contain a null set (i.e., LON=999.99 on each line; LAT=99.99 on each line).

Line 8-n: Varies depending upon whether file is for QPF or probability

Line 8-n for QPF: LON LAT RAIN

• LON/LAT - is the position in longitude/latitude of the rainfall calculated
• RAIN - amount of rainfall in inches

Line 8-n for Probability: LON LAT PROBABILITY

• LON/LAT - is the position in longitude/latitude of the probability calculated
  PROBABILITY - probability expressed as an integer from 0-100

  Note: In both the QPF and probability files, line 8 through line n contains a sorted list of longitude/latitude points. The longitude/latitude points cover a square area and are listed from the lower left corner of the rainfall grid to the top right corner.

 

Sample text files, McIDAS area files and gif files can be accessed through the following site:
https://satepsanone.nesdis.noaa.gov/pub/TRAP/ETRAP/example/

By way of example, file names have the following form:
.....2009BIJLI.p100.04161200.00.GIF
.....2009BIJLI.p100.04161200.00.Z
.....2009BIJLI.p100.04161200.00.TXT.Z

With the exception of the gif image, the files are compressed as indicated by the .Z at the end of the file names. Text files are indicated by .TXT. Files not containing the .TXT are McIDAS area files. PC users can use WinZip to uncompress/unzip the files, which will launch automatically after clicking on a compressed file. In Linux/Unix, in the directory where the file is located, type uncompress <file_name> as in the following example:

uncompress 2009JADE.p100.04110000.00.TXT.Z

File names can be interpreted as follows:

 Year  Product Type   Time Period     
   |       |           |                                      
2009JADE.p100.04110000.00.TXT.Z
      |            |                       
  Storm Name   MMDDHHMM (i.e., 2 digit month, 2 digit day, 2 digit hr, 2 digit minute)     

The storm name could be a name as in the example above or an alphanumeric (e.g. 28S) if the system is only of tropical depression intensity. The time the eTRaP is valid is of the form MMDDHHMM. The product types are as follows:

• p<xx> or p<xxx> -- probability rainfall amounts will exceed xx or xxx millimeters.
• pmqpf � probability matched rainfall amounts for a given time period.

The time periods for both probabilistic forecasts and rainfall amounts will be:

• 00 for 0-6 hour time period;
• 06 for 6-12 hour time period;
• 12 for 12-18 hour time period;
• 18 for 18-24 hour time period
• 24 for the 24 hour cumulative time period.