<p>Recently, a 1.55-μm pulsed coherent Doppler LIDAR system using all fiber optical components was developed to achieve real-time measurements of wind fields. The system employs 100-μJ pulse energy at 10 kHz pulse repetition rate. In addition, the system consists of a fiber-based optical transceiver unit, a two-axis scanner, and a multicore digital signal processor (DSP) for real-time signal processing. With compact and mobile design, the LIDAR is easy to transport and deploy for different field campaigns. For a different application of LIDAR, the range resolution can change manually. A horizontal detection range of 10 km is achieved with the temporal and spatial resolution of 1 s and 30 m, respectively. Field experiments compared with an anemometer show that correlation coefficient of the different wind speed measurements is 0.953; the correlation coefficient for wind direction values is 0.967. Continuous wind profiles of the planetary boundary layer are presented to demonstrate the stability of the system.</p>
Direct-detection Doppler LIDAR has been demonstrated for its high temporal and spatial resolution in atmosphere wind detection from troposphere to stratosphere. As Doppler frequency is a relative value, the zero point drift would lead to wind velocity error. So the zero Doppler correction was necessary for high-accuracy wind measurement. We analyzed the reasons that would cause zero point drift and demonstrated a designed Fabry–Pérot interferometer and front optics to measure Rayleigh scatter laser and emitted laser frequency in the meantime. Wind observation experiments were demonstrated in XinJiang, China, and the measured wind profile coincided well with radiosonde results.
A modification method is described for Rayleigh Doppler lidar wind retrieval. Compared to the double-edge theory of Korb et al. [Appl. Opt.38, 432 (1999)] and the retrieval algorithm of Chanin et al. [Geophys. Res. Lett.16, 1273 (1989)], it has a greater sensitivity. The signal-to-noise ratio of the energy monitor channel is involved in error estimation. When the splitting ratio of the two signal channels is 1.2, which usually happened during wind detection, it will improve the measurement accuracy by about 1% at 30 km altitude for a Doppler shift of 250 MHz (44 m/s ). Stabilities of retrieval methods, i.e., errors caused by the spectrum width deviation including laser pulse, Rayleigh backscatter, and filter transmission curve are first discussed. The proposed method increases the resultant precision by about 15% at 30-km altitude assuming an 8-MHz deviation in full width at half maximum of the Fabry–Perot interferometer.