3.19.2013

Introduction Wave Breaking

Most readers will associate wave breaking with breaking surf at shallow beaches. This article, however, deals with breaking wind waves in deep water where wave and turbulence fields are not affected by the presence of the seafloor.
Introduction Wave Breaking

Deep-water surface waves are sometimes compared to a gearbox linking the atmosphere to the oceans. In this analogy, breaking waves would indicate a high gear. They play a dominant role in many upper ocean processes, such as momentum transfer from wind to ocean currents, dissipation of wave energy, entrainment of air bubbles, disruption of surface films, and the generation of sea spray and aerosols, besides being a source of ambient noise.
Wave breaking causes enhanced turbulent kinetic energy levels in the near-surface layer and thus governs turbulent transport of heat, gases, and particles in the near-surface zone. The forces exerted by breaking waves on ships and offshore structures are up to 10 times larger than for nonbreakers, and especially larger breaking waves pose significant danger to seafarers.

Turbulence generated by breaking waves is very intermittent and coexists with turbulence generated by other sources such as shear stress, convection, internal waves, and Langmuir circulation. Presently, it is not understood how wave-induced turbulence interacts with this background turbulence, and these complex interactions are not discussed in any detail in this article.