Enhanced Passive Tracer Dispersion by an Energetic Internal Wave Continuum

Abstract In this work we explore the impact of a broad spectrum of internal waves on the dispersion of passive tracers. We do so by looking at tracer dynamics in low Rossby number flows with different balance‐to‐wave energy levels generated by numerically integrating the Boussinesq equations. Our tracer dispersion experiments reveal that stirring, dispersion, and downscale cascading of tracers are enhanced on increasing wave energy level in the flow. Specifically, wave‐dominated flows exhibit higher tracer spectral flux, steeper tracer variance spectra, and severe depletion of tracer variance across scales, compared to eddy‐rich flows. Interestingly, our analysis also show that the dominant share of the tracer flux is located in regions of low vorticity values in eddy dominated flows and low horizontal divergence values in wave dominated flows. These findings point out that internal wave‐induced effects on tracer dispersion cannot be neglected and needs to be accurately parameterized in large‐scale models that do not directly resolve wave fields.