Oceanic Mixed Layer Response to Tidal Period Internal Wave Motion.

The purpose of this research was to investigate the effect of tidal-period internal wave vertical motion on oceanic mixed layer dynamics, and to discern the effect upon the diurnal evolution of thermoclines, as observed during MILE mixed layer experiment. Vertical advection was added to a one-dimensional bulk model of the mixed layer with an assumed linear in z and sinusoidal in time dependence. The rate of mixed layer deepening was therefore due to the combination of vertical motion and entrainment. The first significant result was the finding that the interaction between vertical mixing and vertical motion depended upon the wave frequency and its phase relation to the diurnal heating cycle. Second, linear and non-linear interactions of the wave induced vertical motion with the cyclical boundary conditions can generate two-dimensional x-z structure in the near-surface temperature field of an initially horizontally homogeneous ocean under the influence of horizontally homogeneous surface boundary conditions. Finally, this advective interaction increases the utility of the mixed layer model in single station forecasting. Author