This is an old revision of the document!
Table of Contents
Ceilometer Jenoptik CHM15k Nimbus
Mentor: NN
Principle
A ceilometer measures the cloud base height, i.e. the ceiling in aviation. It is based on the light detecting and ranging (LIDAR) principle, i.e. it sends laser pulses and measures the backscattered light. From travel time the distance of the back scattering object can be determined. From strength and attenuation of the backscattered signal the backscatter coefficient is determined. The instrument identifies cloud bases by the strong increase of the backscatter coefficient. If the lower clouds are transparent it can detect up to three distinct cloud layers. We use the backscatter profile for an estimate of boundary layer height.
Instrument
Current setup at Research Center Jülich on the roof of IEK-8: Jenoptik CHM15k ceilometer.
Data
History
| Period | Place | Project |
|---|---|---|
| 03/2013 - today | Research Center Jülich, Germany | TR32 |
Specifications
| Parameter | Specification |
|---|---|
| Wavelength | 1064 nm |
| Bandwidth | 0.1 nm |
| Pulse duration | 1 … 5 ns |
| Pulse repetition rate (prr) | 5 - 7 kHz |
| Beam diameter | expanded to: 90 mm |
| Laser divergence | < 0.3 mrad |
| Energy per pulse | 8µJ |
| Long-time stability over 12 month (prr) | < 10 % |
| Pulse to pulse variance of laser energy | < 3 % |
| FOV Receiver | 0.45 mrad |
| Voltage | 230VAC, +/- 10 % / 50 Hz |
| Max. power consumption | 0,8 kW (all heater are running) |