here you can find discussion about calibration issues (Rayleigh and cloud calibration )

Frank Wagner and Maxime Hervo are responsible for this page

First results

Using molecular signal for instruments measuring at 1064nm and cloud signal for instruments at 910nm, ceilometers measuring in June 2015 during at the Ceilinex campaign were calibrated.

ALc calibration

The difference between the instruments was reduced from 3 orders of magnitude to ~50% difference.

More precise results can be obtain using a reference Lidar, but with this method all instruments in Europe can be calibrated without any intervention on site.

After the SWG in Paris, the algorithms will be improve to reduce the uncertainties.