Cloud-Base Height Measurements with a Single-Pulse Erbium-Glass Laser Ceilometer

A cloud ceilometer using a solid-state laser was developed by the French meteorological office in association with Sfim ODS. The transmitter is an eye-safe erbium-glass laser operating at 1.54 μm. Cloud-base heights are deduced from extinction profiles calculated by the Klett lidar inversion algorithm. The inversion process is carried out in successive steps—first the high isolated clouds and then the lower part of the atmosphere. For each step a clear-air extinction boundary value is chosen. Temporal and statistical comparisons of the erbium-glass laser ceilometer with conventional ceilometers of the French network using flash-lamp or GaAs laser-diode transmitters are presented. Under nonprecipitating conditions, cloud-base height comparisons show very similar results; but when precipitation is present, the erbium-glass laser yields a significant performance improvement over the laser-diode ceilometer.