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 modewithin 1.1-2.3 m/s, and the waves of the third modewithin 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.
The mechanism of generating barotropic long waves on the Black Sea Turkish coast is studied. Influence of the shelf shape and width upon the spatial-temporal parameters of the edge waves' lower modes is noted based on solution of the complete boundary-value problem using the developed algorithms of the finite-difference approximation. To simulate the generated on the Anatolian coast waves induced by the climatic wind, the three-dimensional model (for the Black and Azov seas) of the Institute of Numerical Mathematics of RAS is used. Position of the wave attenuation points and maximums of the level oscillations' amplitudes depending on the topography feature in the boundary area (the shelf and the continental slope zone) are studied. It is shown that the profile absolute maximum of the first mode wave is achieved at the coast and above the shelf edge. Increase of the continental slope width leads to slower decay of a wave towards the open sea. Convergence of the dispersion curves at high frequencies for various widths of the shelf is demonstrated. At the intermediate frequencies on the wide shelf, the dispersion curves are horizontal and their group velocity is close to zero. Having been studied, the spatial-temporal characteristics of the edge waves at real bottom profiles show that the waves with the longest periods arise in the region of the Ince Burnu that is due to manifestation of the zero mode of the trapped edge waves. The graphs of the dispersion curves and the maps of the amplitude functions of the shelf modes are constructed for the Anatolian coast. The model time series of the sea level are analyzed to calculate spectral density of the water level oscillations' power at the coast using the fast Fourier transformation. The spectra of the level oscillations' amplitudes for the shelf and deep sea stations of the Anatolian coast are represented.
Проведено моделирование гидродинамическое процессов в Черном море в 2017 г. с использованием реальных атмосферных данных модели реанализа Skiron. Численные расчеты выполнены на основе трехмерной нелинейной σ-модели циркуляции океана INMOM. Выходные данные модели сравниваются с данными наблюдений поверхностных проявлений внутренних волн, зарегистрированных в прибрежной зоне Южного берега Крыма со спутников Landsat-8, Sentinel-2 в 2017 г. Проведен анализ изменчивости модельных полей температуры и скорости течений в районе обнаружения поверхностных проявлений внутренних волн на спутниковых снимках. Выполнен спектральный анализ колебаний уровня Черного моря и кинетической энергии течений на шельфе Крымского побережья. Выявлены детали баротропной региональной динамики приливов K1, M2, реконструированные по модельным данным в исследуемом регионе.
This work investigates the regional specifics of the appearance and propagation of internal waves at the shelf of the Black Sea. The parameters of horizontal inhomogeneity associated with changes in the bottom relief and density of seawater that lead to instability and destruction of internal waves are studied. The numerical experiments for the spring and summer seasons on transects normal to the coast are conducted using data of temperature and salinity from the Bank of oceanographic data of the Marine Hydrophysical Institute of RAS. The article touches upon the actual theme of adaptation of satellite images obtained from open sources when solving oceanographic problems. The result of the processing of remote sensing data was information about the speeds and wavelengths for the observed phenomena. These values are used to recover the depth of the seasonal pycnocline within a two-layer approximation of the vertical density structure. For different bottom slopes and seasonal profiles of the buoyancy frequency, sites are determined where the transition from supercritical to critical or subcritical conditions is possible in the region of the Crimean coast.
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