ESA Data Ontology: ESADO: HIFT

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HIFT

THE HEARD ISLAND FEASIBILITY TEST (HIFT) was developed to study the propagation of underwater sound waves across whole oceans, possibly as a means of monitoring ocean temperatures on a large scale. (The speed of sound in water depends on the water temperature.) In January 1991 a series of coded sound waves was transmitted from an underwater station near Heard Island in the southern Indian Ocean. The waves were later detected across a network of 16 sites (some on board vessels at sea) positioned along great-circle sightlines (or perhaps soundlines would be a more appropriate term) around the world. One example: the signal took 2.95 hours to reach the Bermuda station 16,000 km away. The researchers were generally satisfied with the quality of the received signals, as measured by the signal-to-noise ratio and the stability of the waveform over time. They suggested, however, that for monitoring ocean climate variability acoustic thermometry should be integrated with satellite me! asurements. On another point of concern, the scientists found no evidence that the sound transmissions produced any distress among local marine mammals. (17 papers in the Journal of the Acoustical Society of America, October 1994; introduction by Walter R. Munk of Scripps and Arthur Baggeroer of MIT.) (en)

https://gcmd.earthdata.nasa.gov/kms/concept/cb0d5e6f-ae97-4de5-b89a-d72333c56963

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