How a Small Reef in the Kuroshio Cultivates the Ocean

D. Hasegawa, T. Matsuno, E. Tsutsumi, T. Senjyu, T. Endoh, T. Tanaka, N. Yoshie, H. Nakamura, A. Nishina, T. Kobari, T. Nagai, X. Guo

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13 Citations (Scopus)


Vertical nitrate fluxes associated with turbulent mixing and upwelling around a small reef in the Kuroshio are quantified by continuously deploying a turbulence microstructure profiler with an attached submersible ultraviolet nitrate analyzer while drifting from the upstream to the downstream of the reef. Flow separations and trains of Kelvin-Helmholtz billows (thickness = 60 m) are identified using a shipboard ADCP and an echo-sounder. The turbulence diffusivity associated with the vigorous turbulent mixing reaches up to O(10−1 m2 s−1), resulting in strong nitrate fluxes of O(1–103 mmol m−2 day−1). In addition, large differences between the upstream and downstream density profiles suggest a strong upwelling velocity of O(10−3 m s−1), as well as an upwelling nitrate flux of O(102 mmol m−2 day−1) in the entire subsurface layer.

Original languageEnglish
Article numbere2020GL092063
JournalGeophysical Research Letters
Issue number7
Publication statusPublished - Apr 16 2021

All Science Journal Classification (ASJC) codes

  • Geophysics
  • General Earth and Planetary Sciences


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