资源环境科技发展态势分析平台

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 (altitude = 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 to 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.