this discussion is lead by Frank Wagner, DWD

Example using low clouds

Not so loo clouds

Note that the scaling of the profile for each individual device is different. Comparisons can be done through the subplot on the right right of each figure.

The cloud attenuated backscatter for Jenoptik/Lufft devices is about 1 order of magnitude lower than for Vaisala and Campbell ceilometers. The effect is caused by detector saturation effects related to photon counting.

Surprising is that the Jenoptik/Lufft ceilometer CHX080082 doesnt has this effect.

Surprising is also the different shape of the profiles between CS1 and CS2.

For comparison and to highlight the effect, the attenuated backscatter profile of not so low clouds are provided. The values for each device within a cloud differ much less.

Please note that detector saturation is not a problem for the detection of clouds. However it is an issue regarding the calibration method using water clouds and for providing attenuated backscatter within clouds.