SUB-HARMONIC TRANSITIONS AND GROUP FORMATION IN A WIND WAVE FIELD

Laboratory experiments in which waves from a mechanical wave generator were injected at the upwind end of a fetch-limited wave field. The injected wave groups appear to grow at the expense of the ambient wind wave field, and the wind profiles in the boundary layer show large fluctuations when waves are injected. The effects observed appear to demonstrate the sensitivity of nonlinear modulational dynamics of surface waves to weak disturbances.