Targeted Doppler lidar observations during NA-TReC (14-28 November 2003)

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System



The Doppler lidar system of DLR measures vertical profiles of the 3-dimensional wind vector (u,v,w). The profiles are obtained by the velocity-azimuth display (VAD) technique. The system performs a conical step and stare scan around the vertical axis, and measures the velocity in the pointing direction at 24 positions (Line-Of-Sight velocity). Then a wind profile is calculated for every scan revolution. The accumulation time is one or two seconds at every position (500 and 1000 pulses respectively), which reduces the speckle noise. One scan takes about 30 or 60 s (24 times 1 or 2 s + a few seconds for the scanner motion), which corresponds to a horizontal resolution of 6 or 12 km (aircraft speed ~ 200 m/s). The vertical resolution of the profiles is 100 m.


DevelopmentDLR, CLR Photonics
LaserTm:LuAG
Wavelength2.02254 µm
Energy:1.5 mJ
Repetition rate500 Hz
Pulse length600 ns FWHM
Vert. resolution100 m
Telescope diameter0.1 m
Power · aperture6 mW m²
Nadir angle20°
OperationConical scan or
const. azimuth angle
Accuracy of horiz. wind speed< 1 m/s