We analyze turbulent overturns in the high-shear, low Richardson number flow of the upper 350 m at 0¿/140 ¿W. Profiles of shear and stratification combined from fine- and microscale sensors resolve the vertical wavenumber spectrum from large-scale to dissipation scales. We compute a turbulent length scale l from Thorpe-sorting potential temperature, while using potential density to avoid thermohaline intrusions. Pragmatically, we consider scales smaller than l turbulent and scales large than l nonturbulent. From local fine-scale velocity spectra, we extract the horizontal turbulent kinetic energy at scales smaller than l and thus estimate the turbulent velocity q, a parameter characteristic of the energetic eddies. The independently observed viscous dissipation rate &egr;, q, and l follow Taylor scaling, &egr;=cqq3/l, with cq≈4. Similarly, the measured thermal dissipation rate &khgr; and the turbulent temperature fluctuation T', also estimated by spectral extraction at scales smaller than l, follow similarity scaling, &khgr;=ctT'2q/l, with ct≈7.

From q,l buoyancy frequency N, and kinematic viscosity &ngr;, we estimate turbulent Reynolds numbers Ret=ql/&ngr; and turbulent Froude numbers Frt=q/(Nl). The more energetic overturns of vertical thickness exceeding 1 m have 0.1≲Frt≲3 and 250≲Ret≲105. Ozmidov scales follow overturning scales as described by Dillon (1982) only on average, but not in individual overturns. Richardson numbers Ri of overturns show large scatter around a median of Ri=0.23 and virtually no correlation with &egr;. The mixing efficiency shows a weak increase with increasing Ri and a weak decrease with increasing Frt. Turbulence parameters are briefly compared with formulations in turbulence closure models. A few individual mixing events are analyzed in detail, with focus on possible forcing mechanisms. In such identifiable events, enhanced turbulence is paralleled by enhanced fine-scale variance of velocity, shear, and temperature. One mixing event shows signatures of critical layer absorption. A very large overturn in the nighttime turbulent layer near the surface surprisingly shows dissipation rates indistinguishable from the surroundings. ¿ American Geophysical Union 1995