Vaisala Lidar Ceilometer CL61 is a high-performance light detection and ranging (LiDAR) instrument with depolarization measurement capable of unattended operation 24/7 in all weather conditions. The depolarization measurement capability enables clear liquid/solid differentiation for particles and clouds, providing ready-to-use information for atmospheric characterization.
The ceilometer uses pulsed diode laser LiDAR technology where short, powerful laser pulses are sent out in a vertical or near‑vertical direction. The reflection of light, backscatter – caused by clouds, precipitation, virga, haze, fog, and aerosols – is measured as the laser pulses traverse the sky. The ceilometer processes these returns and reports the resulting profiles of attenuated backscatter, linear depolarization ratio and cloud base heights.
The ceilometer detects up to 5 cloud layers simultaneously. If the cloud base is obscured due to heavy precipitation or fog, the ceilometer reports vertical visibility. There is no need for adjustments in the field. The embedded software includes several service and maintenance functions and gives continuous status information from internal monitoring.