White Papers

Verification of wind energy related measurements
with a SODAR system

Complex terrain and growing wind energy converters (WEC) in wind parks generate increasing interest in determining wind profiles and turbulence besides the general forecast of annual energy production. Increasing hub heights and growing rotor diameters of advanced WEC make SODAR systems a valuable alternative to meteorological towers. SODAR systems provide wind profiles as well as turbulence information over the entire height of large turbines. With SODAR measurements at WEC testing field in Grevenbroich in comparison to sonic and cup anemometer the usability of qualified wind and turbulence data from a SODAR are verfied...More »

Wind Energy Application

In the late 1990's, wind turbines with nacelle heights exceeding 60 meters were introduced to the wind energy communicty. Initially, wind prospecting and siting studies continued to use 50-meter wind towers and extrapolate the measurement to the nacelle heights. It was quickly determined that this approach was not sufficient for the placement of these tall turbines. The next approach was to increase the wind tower heights to between 80 meters and 100 meters. In this case the initial financial investment (100 meter towers, installation, etc.), the required FAA permits and tower safety equipment, the increased need for larger land areas coupled with the visibility of these towers in the local community area are reasons to seek alternative measurement methods...More »

A Brief Statement of Airport Applications for Doppler SODAR systems

Operating similar to a sonar the Doppler SODAR (Sonic Detection and Ranging) directly measures the atmospheric wind speed and direction at multiple altitudes simultaneously. These systems utilize the Doppler effect imposed on the received acoustic signal echoed by the atmosphere for the wind measurements. The Doppler effect is the common observation that the acoustic signal frequency increases (decreases) for motion toward (away) from a receiver. By applying this principle and considering the geometry of the Doppler SODAR system it becomes a cost effective and easily maintained "invisible tower" for wind measurements. learn more »

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The miniSODAR™ is a high-frequency Doppler sodar system that was designed to measure the atmospheric wind profile from 15 meters to 150/200 meters (data is often available to 250 meters) in 5-meter increments. It operates by generating a short tone burst (30 ms to 100 ms) in the frequency range of 4 kHz to 6 kHz. It monitors the low-level acoustic signal echoed by the atmosphere. The echo is processed with for its frequency content. The shift in the received frequency with respect to the transmitted frequency is called the Doppler shift, which is directly related to the radial motion of the echo volume with respect to the miniSODAR™ acoustic antenna (see Figure 1). learn more »

Advanced Offshore Measurements to Support Wind Energy Production, Weather Forecasting, and Emergency Response

Sonoma Technology, Inc. (STI), with support from the Bureau of Ocean Energy Management, is leading a unique partnership of corporate, government, and university researchers to develop a marine environmental observations program in the Gulf of Mexico. The primary goal of this project is to develop a framework of advanced offshore measurements to support emergency response, oil and gas exploration and lease decisions, wind energy research and development, and meteorological and air quality forecasting. read more »