This directory contains vertically-pointing reflectivity data recorded by the 35 GHz RABELAIS and 94 GHz GALILEO during CLARE'98. Quicklooks of the data can be found at /clouds/clare98/chil_various/vertical/quicklooks/index.html.
Profiles of 35 and 94 GHz reflectivity for the aircraft overheads have been calculated and can be found at /clouds/clare98/chil_various/vertical/profiles/index.html. Note that this includes profiles taken by the 35 GHz in between RHIs that are not included in the data pointed to by this page (because of differences in range gate spacing in scanning mode among other things).
If you have any problems, please contact Robin Hogan.
These data were calibrated with the old calibration figures. The most recent calibration (as of 11 May 1999, documented here) has revealed that 2 dB should be added to all 35 and 94 GHz (and 95 GHz GKSS) reflectivity values on this site.
The data has been averaged over 30 seconds. The times reported in the data files correspond to the centre of each 30 second pixel, in UTC. The vertical resolution of the 35 GHz radar is 75 metres and that of the 94 GHz radar is 60 metres. The heights correspond to the centre of the bins and are above mean sea level, although the accuracy is no better than the pulse length of the radar, which is of same order as the range-gate spacing.
The contribution to the measured signal from noise has been subtracted. It should be noted that some rays are missing at 94 GHz because of an intermittent technical problem, although it is quite likely that a few rays were lost due to interference from the airborne KESTREL radar.
Calibration has been performed by comparison with the 3 GHz radar at Chilbolton, which has been calibrated in heavy rain using the non-independence of Z, ZDR and KDP. The result is that 17.5 dB has been subtracted from the raw 35 GHz reflectivity, and 14 dB has been added to the raw 94 GHz reflectivity. The resulting reflectivities are fairly consistent with the values reported by both the GKSS 95 GHz MIRACLE radar and the University of Wyoming 95 GHz KESTREL radar.
The files have been zipped using gzip. The file length varies; the longest uncompressed is 3.5 MBytes long and the longest zipped is 380 kBytes.
The format of the data is extremely simple. Each file is a day of data (although there are many gaps) at one frequency, and consists of a single column of numbers. The first two numbers are integers. The first of these is n, the number of range gates, and the second is m, the number of 30-second profiles in the file. The following n numbers are the heights of the range-gates in kilometres above sea level, and the m numbers after that are the times in decimal hours UTC of each profile. The remainder of the file consists of the n×m reflectivity values in dBZ; the first n numbers correspond to the first profile, the second n numbers correspond to the profile 30 seconds later and so on.
Where no cloud was detected, the reflectivity has been set to -99 dBZ.
Click on the following to download a day of 35 GHz data:
981009_35ghz.dat.gzClick on the following to download a day of 94 GHz data:
981020_94ghz.dat.gz