Array for acoustic tomography of the atmosphere at the Boulder Atmospheric Observatory
Technical Report,10 Jul 2015,09 Jul 2017
University of Colorado - Boulder Boulder United States
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Acoustic tomography of the atmospheric surface layer ASL enables remote sensing and monitoring of the temperature and wind velocity fields. It is based on the measurements of the travel times of sound propagation between acoustic sources usually, speakers and micro-phones, which constitute the tomography array Fig. 1. The temperature and wind velocity fields inside the tomographic region are reconstructed using inverse algorithms. Acoustic tomography is the only remote sensing technique for simultaneous measurements of the temperature and wind velocity fields with subsequent reconstruction of the heat and momentum fluxes. None of the existing meteorological instrumentation enables such remote sensing. The accuracy of tomographic reconstruction of temperature and velocity can be as good as 0.1 K and 0.1 ms, respectively, the temporal resolution can be 0.1 s, and the spatial resolution can be 1 m x 1 m. These resolutions might be increased further by development of the inverse algorithms and more accurate measurements of the travel times. Using several grants from the U.S. Army Research Office, we developed and extended theoretical foundations of acoustic tomography of the atmosphere, such as development of new inverse algorithms and performing numerical simulations of tomography arrays. Furthermore, an array for acoustic tomography of the ASL was built in 2008 at the Boulder Atmospheric Observatory BAO. The BAO tomography array consisted of eight towers located along the perimeter of a square with the side length 80 m x 80 m Fig. 1. Speakers and microphones were installed on the towers at the height of 8 m. A tower in the middle of the array carried a sonic anemometer and temperature probe. Figure 2 depicts one of the towers of the BAO tomography array. A speaker and a microphone are installed at 8 m above the ground. Instrumentation box carries a microphone preamplifier and power outlet.
- Acoustic Detection and Detectors
- Test Facilities, Equipment and Methods