Energy dissipation rate of turbulent kinetic energy was estimated by combining the time series of vertical shear measured by a moored ADCP and numerical simulations. The ADCP was moored at the depth of 2000 m off Joban coast and vertical profiles of velocity were measured for 3 days. The extracted vertical shears were used as time-varying forcing components in LES to reproduce turbulent.eddies Energy dissipation rates obtained from the simulated flow field were in good agreement with those estimated by a conventional model using 10-m shear components. Vertical diffusivity was calculated by simulating the diffusion of dye in the reproduced flow field by LES. Mixing efficiency estimated by comparing the direct and indirect estimates of vertical diffusivities from the results of LES becomes 0.51, which is 2.5 times larger than its upper bound It is found that temporarily large dissipation enhances mean vertical diffusivity, indicating that consideration of temporal variation of flow field is necessary.
