Introduction - Breaking and Dissipation of Ocean Surface Waves - page 11

Figure 1.9 Aerial photo of the ocean surface at extreme wind forcing (Hurricane Isabel). The photo
is courtesy of Will Drennan
with bubbles. The distinct interface is effectively replaced by a two-phase medium and the
notion of wave shape and its singularity become vague.
While breaking due to inherent hydrodynamic reasons still takes place, the wind is now
capable of instigating the process. Additionally, the wind blows away the steep wave crests.
This latter event breaks the surface, creates surface singularities and reduces the wave
energy, but cannot be treated as conventional breaking. Wave breaking and wave energy
dissipation in such extreme conditions are poorly understood even in a phenomenological
sense.
Thus, in order to avoid ambiguity, the wave-breaking process requires more specific
definitions before further discussions are conducted. Therefore, the notion of the breaking
onset, a classification of the wave-breaking phases, definitions of the breaking probability
and breaking severity, types of breaking waves including the concept of micro-breaking,
and breaking criteria will be discussed next in Chapter 2 .