The Kuroshio flowing over seamounts and associated submesoscale flows drive 100-km-wide 100-1000-fold enhancement of turbulence

Takeyoshi Nagai, Daisuke Hasegawa, Eisuke Tsutsumi, Hirohiko Nakamura, Ayako Nishina, Tomoharu Senjyu, Takahiro Endoh, Takeshi Matsuno, Ryuichiro Inoue, Amit Tandon

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

Although previous studies reported that currents over topographic features, such as seamounts and ridges, cause strong turbulence in close proximity, it has been elusive how far intense turbulence spreads toward the downstream. Here, we conducted a series of intensive in-situ turbulence observations using a state-of-the-art tow-yo microstructure profiler in the Kuroshio flowing over the seamounts of the Tokara Strait, south of Kyusyu Japan, in November 2017, June 2018, and November 2019, and employed a high-resolution numerical model to elucidate the turbulence generation mechanisms. We find that the Kuroshio flowing over seamounts generates streaks of negative potential vorticity and near-inertial waves. With these long-persisting mechanisms in addition to other near-field mixing processes, intense mixing hotspots are formed over a 100-km scale with the elevated energy dissipation by 100- to 1000-fold. The observed turbulence could supply nutrients to sunlit layers, promoting phytoplankton primary production and CO2 uptake.

Original languageEnglish
Article number170
JournalCommunications Earth and Environment
Volume2
Issue number1
DOIs
Publication statusPublished - Dec 2021

All Science Journal Classification (ASJC) codes

  • General Environmental Science
  • General Earth and Planetary Sciences

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