NetCDF Sample Data

5 December 2001

The source code for the programs that produced the data on this page is in the chil package (use the latest version) on our software page. The data were plotted as PNG images using the chilncplot program, which aspires to be able to plot all NetCDF radar and lidar data produced by the Cloudnet project, provided that they conform to the Cloudnet NetCDF Conventions.

Galileo radar data

Here is some data recorded by the 94-GHz Galileo radar at Chilbolton: Unzip it using gunzip or WinZip. You can view the contents as ASCII using ncdump; the start of the output of this is shown here. As it should be self-describing, I won't describe it here. This is what the four radar variables Z, v, width and sigma_v look like:

Lidar ceilometer data

Here is some data recorded by the Vaisala 905-nm CT75K lidar ceilometer at Chilbolton: The start of the ncdump output is shown here. The program to produce these data is called ceil2nc and should work with all CT75K data. It outputs two lidar variables: beta_raw, the raw attenuated backscatter coefficient recorded by the instrument, and beta, the same but cleaned of the clear-sky speckle noise that this instrument often suffers from. An example command line would be

ceil2nc -date 20011203 -betacal 2.4 -user "Robin Hogan<>"... 
        -site Chilbolton -elevation 85 c1120222.dat c1120304.dat ...
Note that the -betacal argument does not change the values recorded, it simply puts a value in the scale_factor attributes. The option `-elevation 85' is appropriate for an instrument pointed 5° from zenith.