radcedric −− converts cedric file to common data format file
radcedric −[r|d] [−s]
Radcedric expects a synthesized radar data file produced by the National Center for Atmospheric Research (NCAR) Cedric program on the standard input. A common data format file containing the data in the Cedric file is written to the standard output.
If the Cedric file was transferred to disk using the rtape utility, use the "−r" option. Otherwise, use the "−d" option. (Rtape inserts an 8 byte ASCII byte count before each physical tape record when transferring a tape to disk. The "−r" option uses this fact to speed up processing somewhat.)
The data in the Cedric file is assumed to be organized in terms of horizontal planes, with an entire file devoted to a single time. The output file is rearranged as a three−dimensional array in x, y, and z, one for each field. These fields are output into a single variable slice. An additional scalar variable field called time is defined. This is given the value of the number of kiloseconds after midnight. The static slice consists of 3 index fields, x, y, and z, defining the volume covered by the data.
The project name, latitude and longitude, date, and start time are put in the comment section of the common data format header. The azimuth of the x−axis, the x, y, and z grid spacing, and the location of one corner of the sample volume relative to a reference point are defined in the parameter section. The reference point is at sea level, with horizontal position defined by the latitude and longitude given in the comment section. The corner is the one with the smallest values of x, y, and z, and is the bottom−south−west corner when the azimuth takes its normal value of 90 degrees. Lengths are all in kilometers, velocities in meters per second, and times in units of 1000 seconds. This scaling for time makes velocity times time equal distance with the above choice of units. Reflectivities are in dBZ.
Radar data generally has large regions of missing information due to the lack of precipitation to scatter the radar beam. Cedric’s value for missing data is redefined to be 1000.0 in the output file. This is consistent with the definition of missing data used by the portable graphics system, pgraf.
Radcedric will accept any field names presented by Cedric. For the convenience of UNIX users, they are converted to lower case in the common data format file header.
kestrel%radcedric −r −s < raw > cooked
In this example the Cedric data file "raw" is converted into a common data format file named "cooked". The input file is assumed to have been read onto disk using rtape, and byte swapping is invoked.
Cedric files are machine−dependent as they employ two byte integers to store data, and different machines store these bytes in different order. When reading a Cedric file created on a machine with opposite byte ordering, use the "−s" option. This swaps bytes on all 16 bit integers. A good indication that bytes need to be swapped is if the date listed in the Candis comment has "Weird" for the month.