Measurements and Modeling of Multitone, Low-Frequency Acoustic Data from the Arraial do Cabo Range
NAVAL RESEARCH LAB WASHINGTON DC
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A study was performed to characterize short-range, low-frequency acoustic propagation at the Arraial do Cabo acoustic range, which is located in shallow water on the Southeast coast of Brazil. Acoustic transmission data, obtained by using multitone continuous-wave CW transmissions from uncalibrated sound sources and omnidirectional receivers were compared with predictions of normal-mode acoustic transmission models. The measurements, which were made along the 17- and 47-m isobaths, extended over the frequency range from 12 to 375 Hz. It was found that, for most of the data, short-range multipath interference patterns were in agreement with results calculated by modeling the ocean bottom as a fluid. At frequencies below 80 Hz, the influence of shear waves in the ocean bottom was found to be important for the data taken in water depth 17 m. Recommendations are made to help guide follow-on modeling and experimental acoustic propagation studies. Shallow water acoustic measurements, Acoustic measurement range, Low frequency underwater acoustic propagation, Acoustic modeling.