Relation Of Infrared Doppler Lidar To Remote Wind Measurements In The Turbulent Atmosphere

The performance of a coherent Doppler lidar is affected by the atmosphere. Refractive index inhomogeneities limit the effective aperture of our system to 15.5 cm + or - 4% on the average for a 2.6 km horizontal path 2 m above the surface under daytime conditions. Effective aperture scales as range to the -3/5 power. A differential Doppler technique can measure the wind vector in a single atmospheric volume with three (or mor) closely-spaced beams. This method works even when the distribution of velocities in the volume is wider than the velocity separation from beam angle differences. The structure function for backscatter and wind inhomogeneities scales approximately as r to the 2/3 power between the minimum detectable scale in our experiment and an outer scale of 100 to 500 m, depending on atmospheric condition. (Author).

Radiophysical tools for measuring atmospheric dynamics include sodars, Doppler radars, and Doppler lidars. Among these, coherent Doppler lidars (CDLs) have been considered the best for remote measurement of wind turbulence. This is important not only for understanding the exchange processes in the boundary layer, but also in the applied aspect, such as aviation safety. CDLs significantly extend possibilities of experimental investigation of not only wind turbulence, but also coherent structures such as aircraft wake vortices. The authors of this book conducted field tests of the developed methods of lidar measurements of the wind velocity, atmospheric turbulence parameters, and aircraft wake vortices. This valuable resource, containing over 500 equations based on original results from the authors’ work, gives professionals a comprehensive description of the operating principles of continuous wave and pulsed coherent Doppler lidars. This book studies the possibilities of obtaining information about wind turbulence from data measured by continuous wave and pulsed CDLs. The procedures for estimation are described, as well as algorithms for numerical simulation. Results on the vortex behavior and evolution are then presented.

This Special Issue “Atmospheric Conditions for Wind Energy Applications” hosts papers on aspects of remote sensing for atmospheric conditions for wind energy applications. Wind lidar technology is presented from a theoretical view on the coherent focused Doppler lidar principles. Furthermore, wind lidar for applied use for wind turbine control, wind farm wake, and gust characterizations is presented, as well as methods to reduce uncertainty when using lidar in complex terrain. Wind lidar observations are used to validate numerical model results. Wind Doppler lidar mounted on aircraft used for observing winds in hurricane conditions and Doppler radar on the ground used for very short-term wind forecasting are presented. For the offshore environment, floating lidar data processing is presented as well as an experiment with wind-profiling lidar on a ferry for model validation. Assessments of wind resources in the coastal zone using wind-profiling lidar and global wind maps using satellite data are presented.

The development of selected techniques for the remote measurement of winds, shear, turbulence, aerosols, and temperature and moisture profiles has been outlined in some detail. Emphasis has been placed on techniques that may provide high-resolution data in the vicinity of airbases. A representative and fairly extensive list of references to the evolution of the various techniques has been prepared. The FM-CW radar and CO2 pulse Doppler laser have been identified as valuable for low-level wind and shear measurements. Strong downdraft conditions may be identified through use of infrared thermal anomaly detectors. Temperature and moisture profiles may be obtained through a combination of active sounding for profile inflection points and thermal or microwave multichannel radiometry.

Written by leading experts in optical radar, or lidar, this book brings all the recent practices up-to-date. With a Foreword by one of the founding fathers in the area. Its broad cross-disciplinary scope should appeal to scientists ranging from the view of optical sciences to environmental engineers. Optical remote sensing has matured to become a lead method for cross-disciplinary research. This new multi-authored book reviews the state-of-the-art in a readable monograph.