Analysis of the Spatiotemporal Variability of Wind Wave Frequency Spectra in the Black Sea and the Sea of Azov

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, a database of the spectra for the period from 1983 to 2020 with a time step of 3 hours on an irregular high-resolution computational grid has been created. To describe the variability of the spectra, a classification system consisting of 23 classes differing in peak frequency and spectral density has been developed. Each spectrum in the database is assigned to one of the classes. It has been found out that the class with the lowest spectral density predominates throughout the entire Black Sea and the Sea of Azov, but the percentage of this class varies depending on a region. The second and third most frequent classes also have a low spectral density (to 1 m²/Hz) and differ depending on the location of an analyzed point. On average, the Sea of Azov is characterized by spectra with a higher maximum frequency of the spectral peak as compared to those of the Black Sea. Interannual variability in the frequency of wave classes has varying spatial variance without any significant trends.