Chinese scientists have discovered massive ocean circulation systems off Japan that drive surface wind energy thousands of metres into the deep sea.
The discovery could significantly improve underwater detection, acoustic surveillance and communications for naval operations, according to a report by the South China Morning Post.
Researchers at the Institute of Oceanology of the Chinese Academy of Sciences identified the phenomenon after analysing two years of data gathered by 46 seabed monitoring stations. The monitoring network covered an area of roughly 600 by 600 kilometres in the Kuroshio Extension current region off the eastern coast of Japan, measuring water pressure, deep currents and sound wave propagation.
Undersea energy chimneys
The investigation focused on internal inertial waves, which are created when surface winds agitate the upper ocean. As these waves travel through anticyclonic eddies, they concentrate kinetic energy and channel it downward into deep water, forming vertical circulation structures that the researchers termed inertial chimneys.
Study authors emphasized that the findings prove the deep ocean is not a stagnant body of water. Their measurements revealed that 68 percent of the energy driving near-bottom inertial waves originates in the upper ocean layers, with the remaining 32 percent produced by local currents along the seabed.
The Kuroshio Extension is a powerful oceanic current flowing east from Japan into the northern Pacific Ocean, known among oceanographers for generating intense turbulent eddies. The Institute of Oceanology, part of the state-run Chinese Academy of Sciences, conducts extensive research into maritime circulation, geophysical structures and deep-sea environments.
Impact on naval sonar and surveillance
The findings carry direct consequences for underwater acoustics. The Chinese researchers explained that variations in water temperature and salinity alter the paths that sound waves take beneath the surface and change how quickly acoustic signals lose strength.
Submarines and anti-submarine warfare vessels rely heavily on acoustic sonar to navigate and track targets, because radio waves cannot travel effectively through deep water. Rapid shifts in temperature and water density can create blind spots for sonar operators or bend sound beams away from listening arrays.
According to the authors of the study, linking continuous ocean monitoring with sound propagation models will allow experts to forecast underwater acoustic environments with greater precision. This capability is expected to enhance detection systems for underwater vessels and bolster communication networks, supporting both civilian oceanographic research and naval defence operations.
