Short Range Acoustic Propagation Under Arctic Ice Cover During Icex 16
NAVAL POSTGRADUATE SCHOOL MONTEREY CA MONTEREY United States
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During the Arctic Submarine LabHosted 2016 Ice Exercise, short-range acoustic propagation under ice cover was evaluated. Sound speed profiles were measured and a series of acoustic signals at depths of 25, 50, and 183 meters and frequencies of 950, 2800, and 4050 hertz, respectively, were transmitted from the ice camp. Remotely located vertical line arrays at ranges of approximately 1.5 and 3 kilometers recorded the transmissions. The sound speed profile data obtained at the ice camp were used to model ray paths and transmission loss in the observed frequency, range, and depth combinations. The received signals were processed and analyzed to determine observed variability and transmission loss, which was then compared to the models. A key finding was the presence of a highly variable layer at 50 meters, which was characterized by its effects on sound signals and the sound speed profile. Observations also highlighted variability during transmissions and between trials while finding significant weaknesses in the modeling softwares ability to accurately predict the acoustic environment in the region.