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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: ftp://satepsanone.nesdis.noaa.gov/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:
ftp://satepsanone.nesdis.noaa.gov/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:

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