NCAR / lrose-core

Core C/C++ code for LROSE.
https://www.eol.ucar.edu/content/lidar-radar-open-software-environment
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Incorrect translation of airborne sweepfile to CFRadial #32

Closed mmbell closed 4 years ago

mmbell commented 6 years ago

The Radx I/O does not appear to properly recognize the airborne geometry when reading some Dorade sweepfiles. The old way of identifying airborne geometry is a parameter in the Dorade RADD block called 'scan_mode' which was set to 8 for lower fuselage (type X geometry) and 9 for tail radar (type Y geometry). I think the problem might be that in the updated Dorade format documentation the 'radar_type' is designated as the parameter that contains this info. In the P3 data I have the radar_type is 0 and scan_mode is 8 or 9, so my guess is Radx thinks they are ground-based radars.

The following procedure works to fix the tail radar data: 1) RadxConvert the Dorade file to CFRadial 2) Manually change the NetCDF header to: primary_axis = "axis_y_prime" 3) RadxConvert the CFRadial file back to Dorade or to a different CFRadial file with these flags: -radar_num 2 -apply_georefs -recompute_sweep_angles

If the primary_axis is not changed manually then the RadxConvert flags are not applied during the conversion.

A sample Dorade file from the PECAN project that reproduces this behavior can be obtained here: http://bell.atmos.colostate.edu/PECAN/swp.1150620074119.N43RF-Ta.404.20.0_AIR_v3503