From Lrose Wiki

RadxDiffFields ingests polarimetric radar data and calculates differences between fields.


RadxDiffFields computes statistics about the difference between fields in Radx files. The fields can be in the same file or in different files. The results are written to SPDB as XML.


The following items are required:

  • Polarimetric radar data (any Radx supported format, e.g., cfradial)

Parameter file

RadxDiffFields uses one parameter file that includes the basic parameters related to data location and field names, which is similar to the parameter files for the other Radx applications.

Ensure file is up to date

To obtain the default parameter file, use the following command:

/path/to/lrose/install/bin/RadxDiffFields -print_params > param_file_name

If you already have a parameter file and simply want to check for (and add) updated parameters while retaining current parameters, use the following command:

/path/to/lrose/install/bin/RadxDiffFields -params orig_param_file_name -print_params > new_param_file_name

Important parameters

Input params

  • primary_input_dir: directory containing radar data (if not specified on the command line and if mode = REALTIME)
  • mode: determines if the program waits for new files (REALTIME), moves through start and end times specified on the command line (ARCHIVE), or moves through list of files specified on the command line (FILELIST)

Field details

  • field_pairs: specify the field names and whether the fields are in the same file or different files (along with secondary file path)
  • secondary_file_time_tolerance_sec: time tolerance for finding secondary file to compare with primary data file (secs)
  • secondary_ray_time_tolerance_sec: time tolerance for matching rays between the primary and secondary data sets (secs)
  • secondary_ray_elevation_tolerance_sec: elevation tolerance for matching rays between the primary and secondary data sets (deg)
  • secondary_ray_azimuth_tolerance_sec: azimuth tolerance for matching rays between the primary and secondary data sets (deg)


  • result_percentiles: specify the percentiles to be computed in addition to the mean

Write results

  • write_results_to_spdb: the results will be written in XML, stored in SPDB
  • spdb_output_url: files will be written to this directory

Running RadxDiffFields

To check all command line options for RadxDiffFields, including debugging options and file paths, type the following command into a terminal.

/path/to/lrose/install/bin/RadxDiffFields -h

Once your parameter file is complete, use a command similar to the following to run the application:

/path/to/lrose/install/bin/RadxDiffFields -params param_file_name

The user can also specify the location of cfradial files in the following manner:

/path/to/lrose/install/bin/RadxDiffFields -f /path/to/cfradial/files/ -params param_file_name