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 mu m. 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.