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instruments:wind_lidar

Doppler Lidar

Mentor: J.H. Schween

Principle

The backscattered light from an emitted laserbeam is used to measure wind speed. Analysis of doppler shift gives wind speed along the beam. Combination of several beams allows an estimate of the three components of the wind vector. Amount of received backscattered light allows calculation of backscatter coefficient.

Instrument

Data

  • If you are interested in receiving data please contact the instrument mentor J.H. Schween.

Current VAD plot:
click for more plots

The figure shows a velocity azimuth display (VAD): vectors give direction and speed of horizontal wind at time and height. Vectors pointing upward indicate south wind, vectors pointing to the right indicate west wind. Color shading gives the backscatter coefficient.

History

Period Place Project
12.9.2012 - today Research Center Jülich, Germany TR32
26.7.2012 - 31.8.2012 Engelsdorf, Germany TR32-Patvap
7.11.2009 - 26.7.2012 Research Center Jülich, Germany TR32

Specifications

Parameter Specification Remark
Wavelength / nm 1500nm
Pulse energy / $\mu$J ~100 see ARM handbook
Pulse width / ns (m) 150 (22.5) see ARM handbook
Repetition Rates / s 1/15000 i.e. 15000 laser pulses per second
1.67 avg.beam i.e. N_avg pulses averaged and processed ⇒ dead time=0.67s
300 Doppler Beam swing (DBS) with 3 beams ([azi,ele] = [0,90],[0,75],[90,75])
900 Velocity azimuth display (VAD) with 36 beams ([azi,ele] = [i*10,75])
3600 vertical slice (RHI) with 18 beams ([azi,ele] = [109,i*10])
N_avg 15000 number of pulses to be averaged in one 'beam'
resolution / m 30 range resolution (adjustable from 15m onward)
Field-of-View / deg 360 x 90 free alingment of the beam
maximum range / m 9000 adjustable, but restriced to sufficent backscatter (aerosol, cloud droplets or ice crystals)
velocity resolution / m/s 0.0382 adjustable
velocity precsision / ms$^{-1}$ < 0.20 for SNR < -17dB
max velocity / m/s 19.2 = Nyquist Velocity (adjustable)
Aperture / mm (area /m$^2$) 75 (4.417e-3) see ARM handbook
Size / cm³ 80 x 53 x 40
Average Power consumption / W 140/250 [600] (wo/w Heating/cooling) [The power supply shall provide 600W]
Weight / kg 110 with transport case
Manufacturer Halo Photonics
Instrument streamline V4 Instrument #17
instruments/wind_lidar.txt · Last modified: 2017/11/14 11:55 by jan