Wind LiDAR

from Wikipedia, the free encyclopedia

Wind lidar ( Li ght D etection A nd R was concerned) is an optical remote sensing method for measuring wind speed , wind direction and turbulence . The Doppler effect is used by calculating the amount and direction of wind vectors from the frequency shift between the transmitted and received laser signals due to the reflection from aerosols in the earth's atmosphere . Depending on the concentration of the aerosols present in the atmosphere, wind can be measured over distances of up to several kilometers. In contrast to anemometers , the advantage is, among other things, that measurements can be made over large distances and in spatial detail. In addition, the devices are extremely precise.

Types

The different types of Wind-LiDAR Doppler measurement systems can be classified according to several aspects.

  • According to the type of light emission:
  • According to the number of sensors:
    • Single LiDAR
    • Multi-LiDAR - system made up of several sensors in different locations
  • With wind LiDAR systems, their scan technology and evaluation algorithm can also be described:
    • DBS (Doppler Beam Swing) - the emitted beam is swiveled regularly
    • VAD (Velocity-Azimuth Display) - the speed (radial from or to the sensor) is displayed as a function of the azimuth angle ; in the simple case of a locally constant wind vector, the result is a sinusoidal shape .
    • DVAD (Distance Velocity-Azimuth Display) - the distance from the sensor to the point of scattering / reflection is also included in the analysis and display.

use

Wind LiDAR systems are often used in research and site assessment of wind turbines or wind parks, as well as for measuring wind and turbulence in the area of ​​buildings or bridges. Depending on the intended use, the systems can be installed on the ground, on research platforms in the sea, on wind turbines or on ships. The direction of measurement also depends on the intended use. So serve z. B. LiDAR systems on wind turbines that measure horizontally - that is, along or against the horizontal wind direction - often the detection and investigation of their wake effects on the wind. Due to the good spatial coverage of the wind field, LiDAR systems are often used to validate models such as B. LES - models , which are also often used in wind energy research.

Individual evidence

  1. ↑ a b T Mikkelsen, M Sjöholm, N Angelou and J Mann: 3D WindScanner lidar measurements of wind and turbulence around wind turbines, buildings and bridges . In: Mater. Sci. Closely. (Ed.): IOP Conf. Ser. No. 276 .
  2. ↑ Lukas Pauscher, Nikola Vasiljevic, Doron Callies, Guillaume Lea, Jakob Mann, Tobias Klaas, Julian Hieronimus, Julia Gottschall, Annedore Schwesig, Martin Kühn, Michael Courtney: An Inter-Comparison Study of Multi- and DBS Lidar Measurements in Complex Terrain. In: Remote Sensing. 8, 2016, p. 782, doi : 10.3390 / rs8090782 .
  3. ↑ velocity – azimuth display Glossary, ametsoc.org, accessed February 20, 2019.
  4. ↑ Wen-Chau Lee, Xiaowen Tang, Ben J.-D. Jou: Distance Velocity-Azimuth Display (DVAD) -New Interpretation and Analysis of Doppler Velocity. In: Monthly Weather Review. 142, 2014, p. 573, doi : 10.1175 / MWR-D-13-00196.1 .