Inferring Wave Breaking Dissipation Using Cooling Whitecap Foam: A Proof of Concept*

we present a novel approach for inferring energy dissipation using infrared imagery of the cooling residual foam left behind by a breaking wave. Previous studies have suggested that the visible decay time for the bubble plume of a breaker is correlated with the energy dissipation. In clean water, the plume decay time also correlates with the visible foam decay time; therefore, it is possible to quantify the energy dissipation by measuring the decay time of visible foam for individual breaking waves. But, the relationship between plume and foam decay times in the presence of surfactants is more complex. It has been observed that after a breaking event, the residual foam rapidly cools due to the enhanced evaporative cooling of the upper layer of the foam bubbles. Preliminary experiments suggest that the onset of cooling is not affected by surfactants and the foam starts to cool only after the bubble plume has decayed and no more foam is generated. Here, we present preliminary results from laboratory experiments on the effect of surfactant on the onset of cooling of the residual foam and the relationship between the time from the start of breaking to the onset of cooling, and the bubble plume decay time.