Wave buoy measurements were carried out near the northeastern Black Sea coast at the natural reserve Utrish in 2020–2021. In total, about 11 months of data records were collected during two stages of the experiment at 600 and 1500 m offshore and depths of 18 and 42 m. The measured waves propagate almost exclusively from the seaward directions. Generally, the waves do not follow the local wind directions, thus, implying a mixed sea state. Nevertheless, dimensionless wave heights and periods appears to be quite close to the previously established empirical laws for the wind-driven seas. The results of the wave turbulence theory are applied for estimates of spectral energy fluxes and their correspondence to the energy flux from the turbulent wind pulsations. These estimates are consistent with today’s understanding of wind–wave interaction. It is shown that the main fraction of the wind energy flux is sent to the direct Kolmogorov–Zakharov cascade to high wave frequencies and then dissipates in small amounts. Less than $1\%$ of the wind energy flux is directed to the low frequency band (the so-called inverse Kolmogorov–Zakharov cascade), thus, providing wave energy growth.

The spatial and seasonal variability of the wind wave frequency spectra in the Black Sea and Sea of Azov is studied based on the example of the 2020. Frequency spectra were computed with the WAVEWATCH III model on an irregular computational grid. To describe the variability of the spectra, a classification was developed. Twenty-two classes were found using cluster analysis. The classes differ in peak frequency, spectral density value, and shape. Each spectrum from the entire database was assigned to one of these classes. It was determined that the class with the less spectral density prevails in all seasons in both seas. The second most frequently occurring class has spatial and seasonal variability. The Sea of Azov is characterized by classes with a frequency of the main peak higher than in the Black Sea. A greater number of classes are distinguished in the open parts of the seas than in the coastal zone. Additionally, the percentage of spectra with two or more peaks was calculated. The percentage of such classes in the Black Sea does not exceed 1.5% on average, and the maximum is observed in winter (up to 19%) in the southeastern part. In the Sea of Azov, there are no two-peak spectra that meet the selected criteria.

Wave buoy measurements were carried out near the north-eastern Black Sea coast at the natural reserve Utrish in 2020-2021. In total, about 11 months of data records were collected during two stages of the experiment at 600 and 1500 meters offshore and depths of 18 and 42 meters. The measured waves propagate almost exclusively from the seaward directions. Generally, the waves do not follow the local wind directions, thus, implying a mixed sea state. Nevertheless, dimensionless wave heights and periods appears to be quite close to the previously established empirical laws for the wind-driven seas. The results of the wave turbulence theory are applied for estimates of spectral energy fluxes and their correspondence to the energy flux from the turbulent wind pulsations. These estimates are consistent with today's understanding of wind-wave interaction. It is shown that the main fraction of the wind energy flux goes to the direct Kolmogorov-Zakharov cascade to high wave frequencies and then to dissipation in small scales. Less than 1% of the wind energy flux is directed to low frequency band (the so-called inverse Kolmogorov-Zakharov cascade), thus, providing wave energy growth.

The study addresses the spatiotemporal variability of the wind wave frequency spectra in the Black Sea and the Sea of Azov. Using the WAVEWATCH III model,