Do deep-ocean kinetic energy spectra represent deterministic or stochastic signals?

Abstract

In analogy with historic analyses of shallow-water tide-gauge records, in which tides and their higher harmonics are modified by sea level changes induced by atmospheric disturbances, it is shown that deep-sea currents can be interpreted as motions at predominantly inertial-tidal harmonic frequencies modified by slowly varying background conditions. In this interpretation, their kinetic energy spectra may not be smoothed into a quasi-stochastic continuum for (random-)statistic confidence. Instead, they are considered as quasi-deterministic line-spectra. Thus, the climatology of the internal wave field and its slowly varying background can be inferred from line spectra filling the cusps around nonlinear tidal-inertial harmonics, as suggested previously.