Large Aperture Array Measurements of the Vertical Ambient Noise Field
SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA MARINE PHYSICAL LAB
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Use of a large aperture vertical array allows investigation into the fine-scale structure of the directional ambient noise field. Frequency and directional spectral estimates are calculated during the passage of a local storm, providing a detailed study of ambient noise levels at low frequencies as wind speed increases from 2 ms to 12 ms over a 21 hour period. Spectral levels of horizontal beams reflect distant sources. Spectral levels of beams directed toward the surface and the bottom display a threshold type behavior, suggesting the abrupt onset of a source mechanism such as breaking waves. Subsequent thresholds may indicate a change in source mechanism such as the conversion from spilling breakers to plunging breakers.