Unlike in gravity waves, compressibility dominates acoustic waves, while the effect of gravity is negligible.įor those reasons, Kadri says, scientists have generally studied either sound waves in the ocean from a purely acoustic perspective, or surface waves in an incompressible ocean. For example, sound travels by vibrating and pushing against a fluid medium. A common example is an ocean surface wave.Īcoustic waves, by contrast, propagate through longitudinal compression. “Since acoustic-gravity waves are so much faster than tsunamis or rogue waves, successful recordings of … acoustic-gravity waves would enhance current warning systems dramatically, and improve detection by minutes to hours depending on the source location,” Kadri says, “either of which is sufficient to many lives.”Ī gravity wave is generated in a fluid or at the interface between fluids, and is governed by gravity. Kadri adds that such awareness may help scientists devise early-warning systems for seaside communities and offshore facilities vulnerable to tsunamis or rogue waves - monster waves that can come on suddenly, with potentially devastating effects. “To sustain a healthier global ecosystem and environment, there is a need to increase awareness of acoustic-gravity waves and deep-water transport.” “Deep-water transport is so vital - not only to local marine ecosystems, but to our global ecosystem and environment - that a cut in such transport will ultimately result in the death of marine life, create regions of extreme water temperatures, and dramatically affect our climate,” says Kadri, who has published his results in the Journal of Geophysical Research: Oceans. Based on his calculations, Kadri found that acoustic-gravity waves can push parcels significant distances, depending on their depth. Usama Kadri, a postdoc in MIT’s Department of Mechanical Engineering, tracked the theoretical movement of fluid caught up in an acoustic-gravity wave at various depths in the ocean, ranging from hundreds to thousands of meters below the surface.
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