Comparison of an analog direct detection and a micropulse aerosol lidar at 1.5 - μ m wavelength for wind field observations—with first results over the ocean

Abstract

The performance of two direct-detection atmospheric lidar systems with very different methods of generating and detecting laser radiation is compared as the result of a field experiment held in March 2015, in Chico, California. During the noncontinuous, 11-day test period, in which the systems operated side by side, the micropulse lidar was operated at its maximum pulse repetition frequency (15 kHz) and integrated elastic backscatter over the interpulse period of the analog direct-detection lidar (0.1 s). Operation at the high pulse repetition frequency resulted in second-trip echoes that contaminated portions of the data. The performance of the micropulse lidar varied with background brightness-as expected with a photon-counting receiver-yet showed equal or larger backscatter intensity signal-to-noise ratio throughout the experiment. Examples of wind fields and time series of wind vectors from both systems during the Chico experiment are presented. In addition, scans over the ocean that were collected by the micropulse lidar during a subsequent deployment on the northern California coast are presented. We conclude by reviewing the advantages and disadvantages of each system and make some suggestions to improve the design and performance of future systems. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Comments on “Wind Gust Detection and Impact Prediction for Wind Turbines”

“…Based on only two field experiments that we have conducted over land in the Central Valley of California, this condition often occurs at night. We also note that at least one compact and portable aerosol lidar with the required performance is now commercially available and that wind fields derived from it are shown in [7]. As laser, detector, and optical technologies mature, we expect to see improvements in the performance and accessibility to this approach of wind field measurement.…”

“…The quoted statements above ignore the abundance of published evidence of the strong skill of motion estimation algorithms and dismiss the approach for use in meteorological applications [3][4][5][7][8][9]. The literature shows that two numerical techniques (cross-correlation (CC) and wavelet-based optical flow (WOF)) are capable of extracting horizontal 2D-2C vector wind fields from near-horizontal aerosol lidar scans.…”