Running the Radx applications

Running the Radx applications

There are two main features which are important to the user:

Command line arguments

You can obtain the command line usage of an application by invoking the -h or -help command line argument. For example:

    RadxConvert -h

yields the usage.

Run-time parameter file

The Radx applications use the NCAR Table-Driven Run-time Parameter (TDRP) package to handle parameters.

To create a default (or template) parameter file, use the -print_params command line option.

For example:

    RadxConvert -print_params > RadxConvert.params

These parameter files are self-documenting, using comments inserted by the author of the code.

The user edits the default parameter file to control the application to produce the desired behavior.

To run the application, the user invokes the -params command line option.

For example:

    RadxConvert -params RadxConvert.params -start "2009 10 08 12 00 00" -end "2009 10 08 13 00 00"

will convert all of the files between 12 UTC and 13 UTC on 2009/10/08, using the parametes specified in the parameter file.

RadxPrint

RadxPrint allows you to print data from any of the files supported by Radx.

By default, the contents are printed in a generic form, which does not reflect the way the data is stored in the file format.

By using the -native option, you can see the details of how data is stored in DORADE or UF files.

Use ncdump to see the details of how data is stored in CfRadial or Foray netCDF files.

RadxCheck

RadxCheck performs some basic checks on a CfRadial file, to ensure that it conforms with the format specification.

Use ncdump to see the details of how data is stored in CfRadial files.

RadxConvert

RadxConvert allows you to convert data stored in one format to a different format.

See the LROSE data formats page for details of the supported formats.

RadxDiff

RadxDiff performs a logical difference between 2 files supported by Radx. You can set the levels of the checks both on the command line and in the parameter file. This application is intended to check that the information content of the files is consistent, rather than the fact that everything is exactly equal.

To see the exact differences between two files, run:

   RadxPrint -rays -data -f filename1 > /tmp/filename1.txt
   RadxPrint -rays -data -f filename2 > /tmp/filename2.txt

The .txt ASCII files will contain all of the information in the Radx files. Then use the normal unix diff utilities to check for differences between the two. For example:

   tkdiff filename1.txt filename2.txt

Since the output from RadxPrint can be rather long, this procedure might take too much memory. In order to only examine the top of each file, use the following:

   RadxPrint -rays -data -f filename1 | head -n 10000 > /tmp/filename1.txt
   RadxPrint -rays -data -f filename2 | head -n 10000 > /tmp/filename2.txt

RadxEvad

RadxEvad RadxEvad reads in Doppler data from a polar radar file, computes volumetric VAD (VVP) winds and writes them out to NetCDF.

The implementation in Mdv2Vad is based on the paper 'An Improved Version of the Extended Velocity-Azimuth Display Analysis of Single-Doppler Radar Data' by Thomas Metejka and Ramesh C. Srivastava, Journal of Atmospheric and Oceanic Technology, Vol 8, No 4, August 1991. The code is designed to match the terminology in the paper as fas as is posible. Please refer to the paper for a detailed explanation of the method.

RadxMergeFields

RadxMergeFields allows you to merge fields from a primary set of radial files with fields from a secondary set of files.

The ray geometry is determined from the primary data set. If the secondary data set has a different geometry, the data will be mapped onto the geometry of the primary data set.

Radx2Grid

Radx2Grid performs coordinate transformations from the polar grid on which radar data is collected to a regular grid.

The following regular grids are supported:

  • Cartesian grid in (Z,Y,X)
  • PPI grid in (EL, Y, Z) - performs Cartesian transformation on each elevation angle separately
  • Polar grid, regular in (EL, AZ, RANGE)

RadxCov2Mom

RadxCov2Mom computes radar moments from raw covariances. The advantage of storing the covariances is that later on you can go back and re-compute the moments with updated calibration values and improved algorithms.

For this to work, during data acquisition you need to save the covariance fields for the dual-polarization mode you are working in. These details are provided in the default parameter file.

You will also need a calibration file, in XML - see this example

RadxPartRain

RadxPartRain computes the NCAR Particle Identification, and the NCAR precipition estimates, from dual polarization data.

These algorithms need to be tuned for each of the various wavelengths. See the following examples: