Internal Waves on the Black Sea Shelf near the Heracles Peninsula: Modeling and Observation

Abstract

Purpose . The purpose consists in a combined analysis of satellite observations of surface manifestations of internal waves near the Crimean coast and the results of numerical simulation of influence of seasonal thermohaline conditions and the relief on their structure, dynamics and intensification. Methods and Results. Based on the analysis of remote sensing data using high-resolution sensors of the Landsat -8 and Sentinel -2 satellites and the theoretical estimates, the main spatial and temporal characteristics of the internal waves on the Black Sea shelf near the Heracles Peninsula were determined. According to the temperature and salinity data obtained from the satellite measurements and the research vessels measurements in 1951–2008 from the Oceanographic Data Bank of Marine Hydrophysical Institute, the structure of density stratification was investigated, and buoyancy frequency profiles in the shelf and slope area from Yevpatoria to Yalta were obtained. Vertical velocity profiles of internal waves of the first three modes on the shelf were constructed. It was revealed that phase velocity of the internal waves of the first mode in the deep-sea part varied within the range of 2.6–5 m/s, the waves of the second mode – within 1.1–2.3 m/s, and the waves of the third mode – within 0.7–1.4 m/s. The average length of the waves detected from the satellite data was 0.4 km; the longest waves, about 1.1 km, were observed most often between Yevpatoria and Sevastopol, propagating predominantly to the northeast. Within the same train, wave dispersion occurred resulting in the wavelength diminution to 0.1–0.3 km. Conclusions. The stated assumption on the cause of generation of intense internal waves conditioned by the interaction of the Rim Current jet with the shelf edge was confirmed by the results of numerical calculations. Spatial and temporal characteristics of the internal waves, the integrated data of remote sensing and the modeling results make it possible to estimate vertical exchange at the shelf and to determine the depth of the maximum Brunt–Väisälä frequency.