Schematic depicting the mechanism for the boundary current synchroization. The Kuroshio Current is synchronized with the Gulf Stream, which is caused by the north-south flow of the atmospheric jet stream. This causes near-surface temperatures fluctuate. The temperature distribution at the Earth's surface is shown in the red and blue shadings. This tends to be seen when the Gulf Stream or Kuroshio Current are hotter than normal. The synchronization between pendulums is another similar phenomenon. A metronome suspended from a string transmits information about the direction and magnitude of force to each other through the board. The pendulum rods of both metronomes then become aligned. The atmospheric jet stream plays an identical role in boundary current synchronization to this board. Credit: Shoichiro Kido
Researchers from a number of Japanese institutions discovered that the Kuroshio and the Gulf stream are synced on a daily basis. The group published a paper in Science that describes their decades-long study of satellite data from weather and the relationship between these ocean currents. Paola Cessi from the Scripps Institution of Oceanography, University of California has published a Perspective piece about the work of the Japanese team in the same issue of Science.
The Gulf Stream, an ocean current, originates in the Gulf of Mexico. It then extends beyond the southern tip of Florida. The current then follows the east coast of the United States before it collides with currents in North Atlantic Ocean. Kuroshio, which flows south from Japan in the East China Sea, eventually collides with Oyashio (a more northern current). Both currents have been shown to influence weather conditions in northern hemisphere. For example, large storms often occur at points where they collide with colder currents. Researchers have discovered that both currents are synced over a period of a decade.
Researchers studied large amounts of weather data to discover if there was a connection. They also created models to show how they might interact.
They discovered that the energy carried by the westerly jets was a result of the two currents. For example, heat from Kuroshio was absorbed into the atmosphere where it met Oyashio. Storms then formed that moved west to east all the way across the Pacific Ocean. This energy was then carried by the Jet Stream across the continent U.S.A. and to the Atlantic. It collided in the Labrador Current with heat from the Gulf stream, which was then carried into the atmosphere. Because of the distances involved, it took a while for energy from one current to have an effect on the other. However, the final result showed some synchronization between the currents. This could help improve forecasting in northern hemisphere.
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Further information: Tsubasa KOHyama et. al., The Gulf Stream is synchronized with the Kuroshio Current, Science (2021). Tsubasa Kohyama et. al., The Gulf Stream is synchronized with the Kuroshio Current, (2021). DOI: 10.1126/science.abh3295 Paola Cessi, Gulf Stream and Kuroshio synchronization, Science (2021). DOI: 10.1126/science.abl9133 Journal information: Science
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