CAJ | 학술논문

The breaking mechanism of UIIW (usual inertial internal waves) and NIIW (fine-scale near-inertial internal waves) caused by shear instability due to -effect is studied following Part Ⅱ. Physically it resembles very much the process of surface wave breakdown and saturation in the presence of a thin vortical surface drift layer induced by wind stress. Breaking products of UIIW and NIIW with small-scale turbulence form some mixing patches, which is in agreement with observation results of persistent mixing given by Gregg et al. (1986). In terms of Thorpe's (1973) experiments, a method to estimate turbulent kinetic energy dissipation rate and the decay time is developed. The results show that UIIW bring about much weaker turbulent dissipation in shear instability; on the contrary, NIIW play a dominant role in turbulent dissipation. By using the standard total energy density of the internal wave energy spectrum, the dissipation rates and the dacay time of NIIW are obtained, which are closely consistent with PATCHEX measurements. Several problems associated with the breaking mechanism are discussed as well.