Sandy surf zones are among the most energetic and morphologically active environments in the coastal ocean, where wave boundary layer motions, turbulence generation, and sediment exchange jointly regulate shoreline evolution and cross-shore sediment transport. Observations in natural surf zones have demonstrated that sediment suspension is highly intermittent in response to short-duration energetic burst events associated with breaker turbulence. Previous studies have largely examined the generation and propagation of these events at wave or wave-group time scales. Much less is known about whether turbulence bursts in natural surf zone exhibit systematic variability over longer hydrodynamic time scales, particularly across a tidal cycle, during which changes in water depth and ambient current continuously alter wave transformation, breaking processes, and the relative contributions of wave-driven and bed-generated turbulence.

This study investigates the tidal-scale evolution of near-bed turbulence bursts using high-frequency velocity and pressure measurements collected and published during the RealDune/REFLEX field experiments on the Dutch coast. Wave orbit motions and turbulent fluctuations are separated from the velocity records using a phase-based frequency filtering approach. Turbulence burst characteristics, including occurrence frequency, intensity, duration, Reynolds-stress contribution, and quadrant structure, are quantified within consecutive time windows to examine their variability across the tidal cycle and identify potential shifts in the dominant turbulence regime.

The analysis provides a multi-timescale perspective on surf-zone turbulence by connecting individual wave-scale bursts with tidal-scale variability. The results are expected to clarify whether turbulence characteristics derived from conventional short-term observations adequately represent broader hydrodynamic variability and to identify potential tidal dependence in descriptions of near-bed turbulence, momentum transfer, and corresponding sediment processes.