Long-Wave Sea Level Oscillations Study in Sevastopol Bays via in situ Data

Abstract

The paper describes the data set of measurements of sea level oscillations with a discreteness of 1 minute in three bays of Sevastopol: Gollandiya, Karantinnaya and Krouglaya. The period from early October to mid-December, which is the most provided with synchronous measurements, was analyzed in detail. Spectral and wavelet analysis allowed us to confirm the manifestations of the previously described tidal oscillations, as well as the Black Sea seiche. A more detailed analysis of spectral and phase diagrams allowed us to describe the periods at which local eigenmodes are manifested. It is shown that in the considered bays the oscillations caused by tides, global seiches of the Black Sea and shelf seiches occur in-phase. The interaction of the bays on their own periods has an antiphase character. For the first time on the field observations for the Sevastopol bay system, it was shown how the senior modes of a larger bay manifest themselves in the oscillations of adjacent smaller bays. High values of coherence were noted between the oscillations in the Gollandiya and Karantinnaya Bays at the natural periods of Sevastopol bay equal to 48 and 10 min. Krouglaya and Karantinnaya Bays actively interact with each other at the Helmholtz mode periods (11.9 min — Helmholtz mode period of Karantinnaya Bay; 13.5 min — Helmholtz mode period of Krouglaya Bay).