Abstract
In this study, a Navis-MicroRider microstructure float and an EM-APEX float were deployed along the Kuroshio Extension Front. The observations deeper than 150 m reveal widespread interleaving thermohaline structures for at least 900 km along the front, presumably generated through mesoscale stirring and near-inertial oscillations. In these interleaving structures, microscale thermal dissipation rates are very high O(>10-7 K(2)s(-1)), while turbulent kinetic energy dissipation rates E are relatively low O(10-10-10-9 Wkg(-1)), with effective thermal diffusivity K of O(10-3 m(2)s(-1)) consistent with the previous parameterizations for double-diffusion, and, K is two orders of magnitude larger than the turbulent eddy diffusivity for density K. The average observed dissipation ratio in salt finger and diffusive convection favorable conditions are 1.2 and 4.0, respectively, and are larger than that for turbulence. Our results suggest that mesoscale subduction/obduction and near-inertial motions could catalyze double-diffusive favorable conditions, and thereby enhancing the diapycnal tracer fluxes below the Kuroshio Extension Front.