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Science Rendezvous > Posters Effects of Vortices on Sound Propagation R. Michael Jones (1) and Alfred J. Bedard jr. (2) (1) CIRES, (2) NOAA/ESRL/CIRES The presence of a vortex in or near acoustic propagation paths can have profound effects on the distributions of sound energy and cause sound waves to originate from virtual source positions. For example, recent studies have shown that surges of infrasonic energy are emitted from the regions of hurricanes and seem correlated with hurricane intensification and de-intensification. The azimuths measured for a limited number of cases published to date do not seem to originate from the vortex cores; but rather from the periphery of the system. To help answer the question of whether the sound generation mechanism is located outside of the vortex core or whether the sound is being affected by strong wind and temperature gradients with the measured azimuths indicating virtual source positions, we simulated the situation by ray tracing, in which we positioned a sound source at various stations in and near a hurricane-like vortex and examined the ray paths emitted by an isotropic source for a standard atmosphere with and without wind. We found that (1) strong focusing can occur, (2) strong de-focusing can reduce possibilities for detection of acoustic signals, (3) strong refraction can cause virtual source locations, and (4) strong refraction can cause nearby observatories to measure quite different signal characteristics. |
