open access

https://hdl.handle.net/2115/97932

Exceptional heat and basin-scale connections in the Kuroshio-Oyashio region in the early 2020s

英語

Marine ecosystem

2025-06-28

Springer

Journal of oceanography

81(5)

443-461

This study investigates recent extreme conditions in the North Pacific, which began in the late 2010s and have intensified significantly by 2024, focusing on the Kuroshio-Oyashio region. The anomalies appear to have originated in the western North Pacific, linked to changes in the Kuroshio and Oyashio currents, while those in the eastern North Pacific began to develop in a separate and distinct region. Sea surface temperature anomalies in the Kuroshio-Oyashio region have reached record-breaking levels, with deviations up to 6 degrees C above the 1990-2019 average. Subsurface temperatures have also increased notably, accounting for 15.8% and 11.8% in the western and eastern North Pacific (27.6% combined) of the global ocean heat content increase in the 0-300 m layer between 2020-2024 and 2010s. Extreme marine heat waves occurred in coastal water near Japan in 2023-2024, resulting in the largest area-day fraction of extreme MHWs among world basins. In the 2020s, Kuroshio water anomalously intruded northward to approximately 42 degrees N along Japan's coast, forming a loop-like pattern with a southward return flow, while the Kuroshio Extension, over a wider zonal extent, also shifted northward by about 1.3 degrees in latitude. These oceanic anomalies are likely influenced by wind changes, with Sverdrup theory suggesting weakened subtropical and subpolar gyres and a northward shift of the subtropical-subpolar gyre boundary. Further research is needed to fully understand, monitor, and predict these changes and their impacts on regional ecosystems.

学術雑誌論文

Accepted Manuscript

This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: http://dx.doi.org/DOI:10.1007/s10872-025-00764-w

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