Steady nutrient upwelling around a biological hotspot of the confluence between the quasi-stationary jet and the Oyashio in the western North Pacific.
The quasi-stationary jet, a branch of the Kuroshio Extension, transports warm saline water in the mixed water region of the western North Pacific. Around the subarctic front between the quasi-stationary jet and Oyashio and its downstream area is a biologically productive area including small pelagic...
| Published in: | Scientific Reports |
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| Main Authors: | , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Nature Publishing Group
2024
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| Subjects: | |
| Online Access: | https://doi.org/10.1038/s41598-024-68214-z https://pubmed.ncbi.nlm.nih.gov/39080427 |
| Summary: | The quasi-stationary jet, a branch of the Kuroshio Extension, transports warm saline water in the mixed water region of the western North Pacific. Around the subarctic front between the quasi-stationary jet and Oyashio and its downstream area is a biologically productive area including small pelagic fishes. However, how nutrient is supplied to the euphotic zone in this region remains elusive, especially into the quasi-stationary jet. Using high-resolution hydrography sections across the jet, we showed that Oyashio water isopycnally intrudes under the jet around 26.5-26.8 σθ and forms nutrient-rich intermediate water. Upwelling associated with ageostrophic secondary circulation across the front, caused by confluence, uplifts the intermediate water. A local nitrate maximum was also identified inside the jet by the hydrographic observation. Upwelling has been suggested as a precondition for nutrient supply from nutrient-rich intermediate water to the jet through water mixing which potentially sustains high biological production in the downstream. |
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