The role of internal gravity waves in the equatorial current system

Abstract

Using a two-dimensional nonhydrostatic model, experiments were performed to investigate the formation and maintenance of internal waves in the equatorial Pacific Ocean. The simulations show that internal waves are generated in the surface mixed layer by a type of Kelvin-Helmholtz instability that is dependent on both the flow Reynolds number (i.e., shear strength) and Richardson number. The simulated internal waves exhibit a diurnal cycle, following the daily stability change in the mixed layer. Linear theory shows that the horizontal wavelength of the internal waves depends on both the thermocline stratification and the strength of the Equatorial Undercurrent. The simulations show that internal waves can provide an efficient mechanism for the vertical transport of horizontal momentum. -from Authors