Nutrients at Depth Can Be Uplifted by the Kuroshio Large Meander – GWC Mag

Editors’ Highlights are summaries of recent papers by AGU’s journal editors.

Source: Journal of Geophysical Research: Oceans

The Kuroshio, one of the largest ocean currents of the world ocean, transports a tremendous amount of heat, salt, and other organic and inorganic matter. The Kuroshio flows along the southern coast of Japan, meandering by mesoscale fluctuations, but it sometimes takes a characteristic long-lasting path, deflected more than 300 kilometers further south. This large amplitude deflection is known as the Kuroshio large meander, and it may persist for years. As the large meander affects local temperature distributions in the ocean, its impacts on local weather and fisheries have been long-known and widespread. However, underlying physical and biological processes under the sea surface caused by the large meander have still been elusive.

Using an eddy resolving ocean model, Hayashida et al. [2023] show that nutrients, which are usually abundant in depth, can be uplifted in the offshore region of the large meander, making them more susceptible to wintertime mixing near the surface during winter season to promote offshore phytoplankton bloom. This enhanced phytoplankton bloom leads to more export production that could affect CO₂ uptake in this region.

Citation: Hayashida, H., Kiss, A. E., Miyama, T., Miyazawa, Y., & Yasunaka, S. (2023). Anomalous nutricline drives marked biogeochemical contrasts during the Kuroshio large meander. Journal of Geophysical Research: Oceans, 128, e2023JC019697. https://doi.org/10.1029/2023JC019697

—Takeyoshi Nagai, Editor, JGR: Oceans

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