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Mentor: S. Steinke
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.
Current setup at Research Center Jülich on the roof of IEK-8.
|Pulse Power||16 W typical|
|Pulse energy||1.6μJ ±20%1)|
|Average Power||8.9 mW|
|Pulse Width||100 ns|
|Pulse Repetition Rate (PRR):||5.57 kHz|
|Number of pulses (PQTY):||65,5362)|
|Averaging time:||11.7sec (=PQTY/PRR)|
|Time resolution||15sec 3)|
|Range resolution||50ft = 30m (see here)|
|Range||200…25,000 ft. (60…7500 m)|
|Laser Divergence||± 0.53×0.75 mrad (edge×diagonal4))|
|Field-of-View Divergence||± 0.66 mrad|
|Tilting angle||2.5° as of Aug 21 2015 (7° before…)|
|Size||760 x 280 x 245 mm|
|Power Consumption||365 W|