Directional Spreading of Short Wavelength Fetch-Limited Wind Waves

Observations of the spreading of short-wavelength (5 m) wind waves have been made with a steerable HF ocean surface radar in the nearshore zone in a stable offshore airflow. The directional spreading lobe is significantly broader than that predicted from the model by Hasselmann et al. It appears that the spreading lobe is broader at high frequencies (f≈0.56 Hz) than at lower frequencies (0.2<f<0.5 Hz) for f/fm ratios near unity in a fetch-limited wind wave spectrum which has a peak at frequency fm.