page_title: Wind profiler
section_title: Principle
hierarchical_section_title: Wind profiler / Principle
caption_attribution_description: Français&#160;: Schéma de fonctionnement d'un profileur, un radar pointant verticalement, qui sert à mesurer le vent horizontal et le mouvement vertical de l'air. Il fonctionne par diffusion de Braggs des ondes de turbulence. Licensing Source: Diagramme personnel libre de tout droit. Pierre_cb Catégorie:Schémas
context_page_description: A wind profiler is a type of weather observing equipment that uses radar or sound waves to detect the wind speed and direction at various elevations above the ground. Readings are made at each kilometer above sea level, up to the extent of the troposphere. Above this level there is inadequate water vapor present to produce a radar "bounce." The data synthesized from wind direction and speed is very useful to meteorological forecasting and timely reporting for flight planning. A twelve-hour history of data is available through NOAA websites.
context_section_description: In a typical implementation, the radar or sodar can sample along each of five beams: one is aimed vertically to measure vertical velocity, and four are tilted off vertical and oriented orthogonal to one another to measure the horizontal components of the air's motion. A profiler's ability to measure winds is based on the assumption that the turbulent eddies that induce scattering are carried along by the mean wind. The energy scattered by these eddies and received by the profiler is orders of magnitude smaller than the energy transmitted. However, if sufficient samples can be obtained, then the amplitude of the energy scattered by these eddies can be clearly identified above the background noise level, then the mean wind speed and direction within the volume being sampled can be determined. The radial components measured by the tilted beams are the vector sum of the horizontal motion of the air toward or away from the radar and any vertical motion present in the beam. Using appropriate trigonometry, the three-dimensional meteorological velocity components (u,v,w) and wind speed and wind direction are calculated from the radial velocities with corrections for vertical motions.
caption: Orientation of the beams in the case of a three tilted wind profiler
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