Wind-wave generation and growth is one of the most fundamental problems in the air-sea interactions. While a significant amount of theoretical and observational work was performed on this topic, high wind conditions in rough seas remain unexplored. Recent interest in this topic is triggered by development of coupled atmospheric-ocean numerical models that parameterize air-sea fluxes with regard to surface wave field state. Such empirical information is already available for mature and calm seas, but its extrapolation to strong wind forcing, such as hurricane conditions, was found to be unsatisfactory. Indeed, in rough conditions with non-linear wave breaking and spray generation, one would not expect wave related fluxes to behave in a usual way. Thus, the work presented here, focuses on wind-wave momentum transfer in high wind conditions.

The experiments were conducted at the Air-Sea Interaction Salt-Water Tank (ASIST) at the University of Miami. A vertical wave-follower allowed an “Elliott” type of static air pressure sensor to acquire data at a small (1-3cm) constant height from the wave surface. Along with surface slope measurements this data provided direct estimate of wind-wave momentum transfer. 20-30 minutes runs were performed for wind-wave conditions of various winds (U₁₀ up to 35 m/s), dominant wave frequency and steepness. Detailed analysis of wind-wave momentum transfer and non-dimensional spectral wave growth function dependences on wind and wave conditions was performed. The results show significantly reduced momentum transfer in high winds compare to classical expectations.