Steepness of Surface Wind Waves in the Black Sea

Within the statistical description of wind waves, the steepness of individual waves, as well as their crests and troughs, is analyzed. The analysis was performed using data obtained in field conditions via an equipment with a high spatial and temporal resolution, which made it possible to consider short-period waves in a frequency range with an upper limit of 0.5 Hz. It has been shown that the steepness of individual waves can be several times greater than the spectral steepness calculated from spectral moments. The values of average horizontal asymmetry, which is defined as the ratio of the steepness of the leading and trailing fronts, and the average vertical asymmetry, which is defined as the ratio of the steepness of the crest and trough, are greater than 1. At the same time, individual waves are often observed whose horizontal and/or vertical asymmetry is less than 1. Empirical distributions have been constructed for the steepness of waves, their crests and troughs.