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dorade_diff_magn − remove alternating azimuth errors from sweep files in a volume. |
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2 |
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dorade_diff_magn ?sweep_directory? |
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This application searches for an azimuth correction to apply to sweep files in a volume. The correction should compensate for jiggling from sweep to sweep. It computes a cost function for a series of azimuth shifts. Cost is defined as the area weighted root mean square reflectivity difference between adjacent sweeps. Reflectivity is stored in the DZ parameter, unless overridden by the DORADE_PARM environment variable. If given, sweep_directory specifies a directory with DORADE sweep files for one volume. If sweep directory is not given, the application searches for sweep files in the current directory. With the --help option, the application prints usage information and exits. Results are sent to standard output. The application prints the cost for each azimuth shift, the optimum azimuth shift (minimum cost), and the shift to apply to each volume to remove the jiggle. Clockwise sweeps should be rotated by the optimum azimuth shift. Counterclockwise sweeps should be rotated by the same amount in the opposite direction. |
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The application loops through a list of angles which are possible corrections for inter-sweep jiggle. The angles are inidicated in the output. At each iteration, clockwise moving sweeps are shifted by the correction angle, counter-clockwise sweeps are shifted by the negative of the correction angle. The sweeps are then interpolated to a common polar grid on the ground. The cost for the correction angle under consideration is the area weighted root mean square difference between the interpolated sweeps. In pseudocode, this is sum((swp0 - swp1)^2 * area), where the sum is over all bins in the interpolated grid, and area refers to the area of a bin. Thus, bins farther from the radar contribute more to the cost. |
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The application is a script. It runs Tcl with the tcldorade extension. |
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Gordon D. Carrie, user0 at server tkgeomap.org |
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radar dorade azimuth |