CLOUD-BASE HEIGHT MEASUREMENTS WITH A SINGLE-PULSE ERBIUM-GLASS LASERCEILOMETER

A cloud ceilometer using a solid-state laser was developed by the Fren ch 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 l idar inversion algorithm. The inversion process is carried out in succ essive steps-first the high isolated clouds and then the lower part of the atmosphere. For each step a clear-air extinction boundary value i s chosen. Temporal and statistical comparisons of the erbium-glass las er ceilometer with conventional ceilometers of the French network usin g flash-lamp or GaAs laser-diode transmitters are presented. Under non precipitating conditions, cloud-base height comparisons show very simi lar results; but when precipitation is present, the erbium-glass laser yields a significant performance improvement over the laser-diode cei lometer.