Evidence for nonlinear interaction between internal waves of inertial and semidiurnal frequency

Abstract

Observational evidence is presented for pervasive nonlinear interaction between inertial and M2 frequency oscillations in the northeast Pacific. Enhanced currents at the sum frequency (termed the “fM2 frequency”) have the rotary spectral properties of freely propagating waves suggesting permanent energy exchange from the inertial and semidiurnal bands to the fM2 band. The interaction may be responsible for the greater than predicted decay of inertial energy observed in the ocean and may contribute significantly to oceanic mixing.