Estimating the Parameters of Wind Turbulence from Spectra of Radial Velocity Measured by a Pulsed Doppler Lidar

Abstract

The strategy providing an estimation of both the mean velocity and the temporal and spatial spectra of radial velocity from data of the same pulse coherent Doppler lidar is proposed. Theoretical relations taking into account the averaging over the probing volume while estimating the spectra of fluctuations of the radial velocity measured by lidar are presented. The method of estimation of the turbulent energy dissipation rate and the variance of the vertical component of wind velocity vector from the spectra of radial velocity is carried out. The results of the comparative experiments are discussed and used in further studies of wind turbulence in the atmospheric boundary layer during the formation of low-level jets and propagation of internal gravity waves.

Comparison of the results of joint measurements of wind velocity by Stream Line and WPL coherent Doppler lidars

“…Using a time window with a width of W T = 120 ns, from such sequences and the accumulation (averaging) of the raw data over a N probe pulses (laser shots), the correlation functions of the complex lidar signal are calculated for various distances from the lidar. The description of the SNR estimation algorithm is given in [16]. From the correlation functions, using the fast Fourier transform (FFT), the power spectra of the lidar signal with an arbitrarily specified number of spectral channels are obtained [16].…”

“…The description of the SNR estimation algorithm is given in [16]. From the correlation functions, using the fast Fourier transform (FFT), the power spectra of the lidar signal with an arbitrarily specified number of spectral channels are obtained [16]. The position of the spectrum maximum determines the Doppler frequency shift, which is proportional to the radial velocity r V (projection of the wind velocity vector on the probing beam axis).…”

“…During experiments with this lidar, we used both conical scanning with the probing beam and measurements were carried out at a fixed vertical direction of the probing beam axis. Such measurement geometries made it possible to obtain raw data, from which information was extracted on the wind velocity vector and wind turbulence parameters in the ABL [16]. However, the use of an additional PCDL during the experiment would significantly expand the possibilities for studying the dynamics of the ABL.…”

Turbulence Detection in the Atmospheric Boundary Layer Using Coherent Doppler Wind Lidar and Microwave Radiometer

“…Coherent Doppler wind lidar (CDWL) obtains radial wind speed information by retrieving the frequency shift of the received signal after passing through a distance in the atmosphere [40][41][42]. Its reliable performance has been verified in various areas, such as the following: turbulence parameters [43][44][45][46][47], aircraft wake vortices [48], boundary layer height [49][50][51], cloud seeding [52], gravity waves [53,54], low-level jets (LLJs) [44,55,56], simultaneous wind and rainfall detection [57], identifying different atmospheric environments [58], and others [59,60]. Therefore, using CDWL is a promising method for detecting the dynamic part of turbulence with high resolution.…”

Cloud Seeding Evidenced by Coherent Doppler Wind Lidar

“…The Doppler wind lidar as an active optical remote sensing instrument measures the radial velocity accurately; these are primarily applied in detecting windshear [32], turbulence [33][34][35][36], aircraft vortex [37], fog [38,39], the atmosphere boundary layer [40], and gravity waves [41] under clear air conditions [42][43][44][45]. Recently, lidars have been extended to precipitation detection for their ability to detect the aerosol and precipitation signals simultaneously under rain conditions [46][47][48][49][50].…”