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uacvt - Upper air data conversion program


uacvt [parameters...] filename


Command Line Resource Default Description
-h help No Lists basic help information.
-df=filename default .wxpdef Sets the name of the resource file.
-na=name name uacvt Specifies the name used in resource file parsing.
-ba batch No Run program in batch mode
-me=level message out2 Specifies level of messages to be displayed
  • file information - mess
  • station information - out3a
  • not in database - out3c
  • bad date information - out3c
  • decoded report - out4a
  • raw data and format - out4c
-fp=filepath file_path current directory Specifies location of database files.  
-dp=datapath data_path current directory Specifies the location (path) of the input raw data files. This is the location where the ingest program has saved the data files. This may be modified in the name convention file.
-cp=conpath con_path current directory Specifies the location (path) of the output converted data files. This may be modified in the name convention file.
-nc=name_conv name_conv name_conv The name convention file specifies how files are named in WXP. This sets which name convention file to use.
-if=in_file in_file upa_dat Specifies the input file name tag. The default is upa_dat, but it can be modified to any value in the filename convention file. A full name convention can be specified as well.
-ou=output output wxp

Specifies what type of output file is to be created:

  • wxp - WXP ASCII converted file. Name convention set to upa_cvt_wxp.
  • cdf - NetCDF binary converted file. Name convention set to upa_cvt_cdf.
-of=out_file out_file upa_cvt The out_file resource specifies the output file name tag. The default is upa_cvt but it can be modified to any value in the filename convention file. A full name convention can be specified as well.

Also, can specify what type of output file is to be created:

  • wxp - WXP ASCII converted file
  • cdf - NetCDF binary converted file
-pf=file_param file_param User prompt
Batch: use
This specifies how to treat files that exist:
  • Use - use the existing file, don't overwrite. The program terminates when this occurs.
  • Over - overwrite the existing file
  • App - append the information onto the end of the existing file
  • Y - same as overwrite
  • N - same as use.
-cf=cityfile city_file upa.cty Specifies the name of the city database file used for station lookup.

NOTE: Stations must exist in database file in order to be decoded.

-cu=[hour|la] current None This specifies to use current data files. The current filename is based on the name convention. An optional hour can be specified for older data. If la is specified, the program will search back to find the most recent available file.
-ho=hour hour None This resource specifies the exact hour that a data file is valid for. This locks in the start hour for a multi-file sequence.
-nh=num_hour num_hour 0 This specifies the number of hours that will be searched for hourly data.
-dh=decode_hour decode_hour None Specifies a specific decode time when using more than one file.
-id=identifier identifier None Used to decode a specific observation.If not specified, all stations will be decoded.
-pa=param[,param...] parameter None Extra parameters:
  • range:pre:post - specifies time range for valid data. (default: -120:120)
filename None
User Pompt
Batch: current=la
The name of the raw data file to be converted. An optional sequence number can be added to designate the time for non-WXP files.  More than one file can be specified.


The intent of the upper air conversion process is to collate the 6 types of upper air reports into one report for ease of use.  The six products include:

  • TTAA - mandatory level data up to 100 mb (sfc, 1000, 925, 850, 700, 500, 400, 300, 250, 200, 150, 100)
  • TTCC - mandatory level data above 100 mb (70, 50, 30, 20, 10, 7, 5...)
  • TTBB - significant level data up to 100 mb
  • TTDD - significant level data above 100 mb
  • PPAA - mandatory wind level data up to 100 mb
  • PPBB - significant wind level data up to 50000 feet
  • PPDD - significant wind level data above 50000 feet.

The program will first prompt the user for the input raw data file. This file should contain the upper air reports for a given time. The user may specify the input file either via the command line of through the current resource. The input naming convention is specified by the upa_dat tag but this can be changed with the in_file resource.  If the data stretches over an hour, the num_hour resource can be specified to search over multiple files.

Once the input file is determined, the program determines the decode time from the filename specified or that of the current resource. If decode time is different from that of the specified file, the decode_hour resource must be specified. This resource can also be used to set decode time range limits which is useful if decoding data from off times such as 90 after the hour.

The program will then read in the upa.cty database file in order to generate a database of upper air stations. The program  When one of the above products is found, it is decoded and the resulting information placed into the database entry for that station. When all the data files have been searched and decoded, the output is saved to a converted file. The station data is saved with its 3 or 4 letter ICAO identifier for consistency with the other data types. The name convention is determined from the upa_cvt file convention tag. If the converted file exists, the user will be prompted whether to overwrite, append or use the existing file. The append option leaves the current data in the converted file and adds the new station data onto the end of the file. If the use option is specified, the converted file is not modified and the surface data conversion program exits.

The conversion process is silent. By default, none of the output is displayed to the screen as an attempt to speed up the conversion process. A list of decoded stations can be displayed is the out3 message level is set:

Station not in database: 76805
Saving stations...
STA:   BRW WMO: 70026 LAT:   71.30 LON: -156.78
STA:   OTZ WMO: 70133 LAT:   66.87 LON: -162.63
STA:   OME WMO: 70200 LAT:   64.50 LON: -165.43
STA:   BET WMO: 70219 LAT:   60.78 LON: -161.80
STA:   FAI WMO: 70261 LAT:   64.82 LON: -147.87
STA:   ANC WMO: 70273 LAT:   61.17 LON: -150.02

Any stations that were in the data file but not decoded are also listed. It is recommended that these stations be added to the database.

There are two types of output data file types available. The ASCII wxp Flat file data type saves all available information in a columnar format which may be edited with a standard text editor. The netCDF data format is a binary format which may be produced by specifying cdf for the output file type.

NOTE: uacvt must be run before any upper air plotting and gridding programs may be run.


uacvt -cu=la -pf=over -me=print 

This converts the latest upper air data file and overwrites any existing file.

uacvt -cu=la -dh=18 -ho=12 -of=upa3_cvt

This will decode 18Z data from WXP ingested data files. Since the data from the WXP ingestor is saved in 12 hourly files, the hour resource is used to specify which hourly file to use. The decode_hour resource tells the program to decode the 18Z data in that file. The output file type is set to upa3_cvt in order to set the output file type to a 3 hourly converted file. Otherwise the hour will be rounded down to 12Z.

The equivalent from the LDM is:

uacvt -ho=18 -cu=la -of=upa3_cvt

which is much simpler since data is stored by hour.


  • upa.cty - the upper air station location database file


  • upairwx - the surface data plotting program
  • upcalc - the surface data contouring program
  • uacalplt - the surface meteogram plotting program

For further information about WXP, email technical-support@weather.unisys.com
Last updated by Dan Vietor on July 28, 1998