Spatial Structure of Turbulent Mixing in the Northwestern Pacific Ocean

Turbulent mixing in the northwestern Pacific Ocean is estimated using the Gregg-Henyey-Polzin scaling and Thorpe-scale methods. The data sources are the hydrographic observations during October and November 2005. The results reveal clear spatial patterns of turbulent mixing in the study area. High-level diffusivity on the order of 10(-3) m(2) s(-1) or larger is found within the western boundary region, where the Kuroshio flows northward. The width covered by this prominent diffusivity shows an increase from 12 degrees to 18 degrees N. The horizontal distribution of depth-averaged diffusivity in the top 500 m shows enhanced mixing with diffusivity of 6 x 10(-3) m(2) s(-1) south of 9 degrees N where the Mindanao Eddy remains a quasi-permanent feature. These two distinct patterns of diffusivity distribution suggest that the Kuroshio and the Mindanao Eddy are likely responsible for the elevated turbulent mixing in the study area.