Seasonal Variability of Wind Wave Spectra in the Black Sea and Sea of Azov

Abstract

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.