chil2a

This program converts Chilbolton-format radar data to ascii. The processing options are shared with chilplot, chil2nc and loadchil. The ascii files are written in the current directory. In the case of scanning data, separate files are written for each scan, and the filenames have the form FFFFrRRRsSS.dat, where FFFF is the file or tape number, RRR is the raster number and SS is the scan number. Cloud data is grouped by day, and the filenames have the form YYYYMMDD_FF.dat, where YYYY is the year, MM is the month, DD is the day and FF is the radar frequency in GHz.

The file format is very straight forward. First there is a header in which each line is prefixed by a `%' symbol, followed by the data, one line per pixel. A value of -999 means no signal. Here is an example of running the program on some scanning data
corona$ chil2a /cdrom/6421new.dat 27 -polar -41.7 -43.7 -43.7 -minLDR -10 -ZDRcal 1.5 -Zcal 5
Writing 6421r027s01.dat
corona$ less 6421r027s01.dat
%File: 6421
%Raster: 27
%Scan: 1
%Date: 20000609
%Time: 08:23:59 UTC
%System: CAMRa
%Frequency: 3.075 GHz
%Latitude: 51.1445 degrees_north
%Longitude: -1.437 degrees_east
%Altitude: 90 m
%Gates: 300
%Columns: 7
%ScanType: RHI
%MissingValue: -999
%Options: -polar -41.7 -43.7 -43.7 -minLDR -10 -ZDRcal 1.5 -Zcal 5
%Variables: time azimuth elevation range Zh Zdr Ldr
%Units: decimal_hours_UTC degrees_from_west degrees km dBZ dB dB
 8.3999  188.983   20.033   5.250   21.9998    0.9999  -33.4707
 8.3999  188.983   20.033   5.550   21.9998    0.8749  -33.7625
 8.3999  188.983   20.033   5.850   21.9998    0.7499  -34.8718
 8.3999  188.983   20.033   6.150   25.7499    0.7500  -35.4520
 8.3999  188.983   20.033   6.450   25.9999    1.0000  -36.2507
 8.3999  188.983   20.033   6.750   23.4998    0.9999  -33.5094
 8.3999  188.983   20.033   7.050   21.4997    0.4998  -33.4318
 8.3999  188.983   20.033   7.350   19.9995    0.6248  -34.8776
 8.3999  188.983   20.033   7.650   14.2480    0.4990  -33.0289
...
Similarly for cloud data:
corona$ chil2a /data/0090c94d.dat 10 -averays 10 -correctrange -oscillator -Zcal 25 -minelev 85
Writing 20000330_94.dat
corona$ less 
%File: 0090
%Raster: 10
%Date: 20000330
%Time: 10:07:18 UTC
%System: Galileo
%Frequency: 94 GHz
%Latitude: 51.1445 degrees_north
%Longitude: -1.437 degrees_east
%Altitude: 90 m
%Gates: 242
%Columns: 5
%ScanType: Fixed
%MissingValue: -999
%Options: -averays 10 -correctrange -oscillator -Zcal 25 -minelev 85
%Variables: time range Zh v sigma_v
%Units: decimal_hours_UTC km dBZ m/s m/s
10.1218   0.030  -38.2273    0.0007    0.0209
10.1218   0.090  -41.7464   -0.0036    0.0195
10.1218   0.150  -47.0917    0.0064    0.0179
10.1218   0.210  -52.5179    0.0697    0.1815
10.1218   0.270  -47.2476   -0.0107    2.2973
10.1218   0.330  -45.0758   -0.0718    0.4053
10.1218   0.390  -41.7746    0.0653    0.7442
10.1218   0.450  -38.1127   -0.1737    0.6733
10.1218   0.510  -34.3515    0.6613    0.4483
10.1218   0.570  -35.5215    0.7335    0.5868
10.1218   0.630  -41.9991    1.1669    0.4880
10.1218   0.690 -999.0000 -999.0000 -999.0000
...