Amplitude modulation in turbulent wind over water waves

We report on the amplitude modulation phenomenon observed in wind turbulence above water waves, under both the monochromatic wave train and broadband wave field conditions. Wave signatures are found embedded in the instantaneous airflow turbulence velocity through envelopes, which exhibit key wave characteristics such as the wave dispersion relation. Our analysis suggests that amplitude modulation represents a nonlinear influence of waves on the wind, originating from wave–turbulence triadic interactions mediated by wave-coherent motion. Our findings offer a more comprehensive understanding of wind–wave interaction and support improved modeling of the wave-influenced marine atmospheric boundary layer.