The Energy Spectrum of the Current Velocity in the Deep Part of the Black Sea

Doklady Earth Sciences - In 2016–2017, the yearly long measurements of the current velocities were carried out at 100 m depth below the thermocline and at 1700 m depth for the first time,...     

Variability of the volume transport through the Korea/Tsushima Strait as inferred from the shipborne acoustic Doppler current profiler observations in 1997–2007

The 10-year series of observations of currents directed along the Korea/Tsushima Strait, which were measured with an acoustic Doppler current profiler aboard a ferry boat that cruised several times a week between the Hakata (Japan) and Pusan (South Korea) ports, is analyzed. Robust estimation methods are used to separate the tidal signal from the inhomogeneous series of the current data in the problem of the harmonic analysis. The MU2, NO1, PHI1, and J1 constituents have been estimated in addition to the MSF, MF, Q1, O1, P1, K1, N2, M2, S2, and K2 tidal harmonics detected previously. The annual variations in the amplitude of the M2 fundamental harmonic have also been taken into account. The current series cleared from the tidal signal has been processed in order to analyze the spatio-temporal variability of the volume transport through the Korea Strait. The normal annual velocity of the water inflow into the Japan Sea through the Korea Strait was 2.77 × 10⁶ m³ s^?1. The ratio of the flow rates in the eastern and western zones of the strait separated by the Tsushima Islands was 2/3. Considerable seasonal variations in the discharge are observed in the western strait zone: the flow rate annual maximum in October is 1.75 times as high as the minimum in February. An insignificant (not more than 0.1 × 10⁶ m³ s^?1 on average) southward flow can cross the eastern channel. Mesoscale vortices are generated in the lee of the Tsushima Islands when the northeastern current flows around them. The energy spectrum of the total nonseasonal flow rate through the Korea Strait has been constructed in the frequency range of 8–500 days. The spectrum has three significant maximums near periods of 10, 19, and 64 days. It has been indicated that this spectrum flattens at low frequencies (<0.1 day^?1) in the vicinity of the formation of mesoscale vortices behind the Tsushima Islands.     

Study of interaction between intense internal wave solitons in the context of the Choi-Camassa model

Based on the approximated theory developed by the authors to describe the interaction of complex solitons that are formed by kinks, i.e., drops of fields of different polarity, the features of the dynamics of intense internal wave solitons are studied in the context of nonintegrable Choi-Camassa equations. These equations describe the evolution of long internal waves with arbitrary amplitudes in a two-layer fluid. Making allowance for the complex character of the limiting amplitude solitons made it possible to study the dynamics of their interaction as longitudinal (not pointlike) formations for the first time. A series of the features of soliton interaction caused by the complexity of their structure is discovered and explained. These include the appearance of solitary waves with opposite polarity in the collision process, anomalously large phase shifts, etc. The existence of these features is verified by numerical experiments in the context of internal wave models permitting the existence of complex solitons.     

Satellite monitoring of pollution in the Russian sector of the Azov and Black Seas in 2003–2007

The results of satellite monitoring of pollution in the Russian sector of the Azov-Black Sea basin in 2003–2007 are considered. Within the framework of this work, a technology of monitoring the state and pollution of the water environment from satellite information received during this period from Russian and foreign satellites has been developed. With this technology, the coastal pollution parameters and hydrometeorological characteristics of the water environment in the area of observation were mapped operationally; 14 types of different satellite information products were issued daily; and the results were generalized over 3 days, ten days, a month, and a period of observation. Long-term satellite monitoring makes it possible to determine and analyze typical situations of pollution distribution in the coastal waters and to detect new circulation elements that transport pollutants, thus purifying the water environment. For example, for the first time, it was found from satellite data that the contribution of a small-scale circulation of waters of the Russian sector of the Black Sea to the transport and distribution of pollutants is commensurable with the contribution of the Main Black Sea Current and coastal anticyclonic eddies. The regularities in the dynamics of pollution distribution promote the increased reliability of charting of the environmental situation, including the prediction of dynamics of pollution spreading.     

Short-term hydrophysical and biological variability over the northeastern Black Sea continental slope as inferred from multiparametric tethered profiler surveys

This presentation introduces a new ocean autonomous profiler for multiparametric surveys at fixed geographical locations. The profiler moves down and up along a mooring line, which is taut vertically between a subsurface flotation and an anchor. This observational platform carries such modern oceanographic equipment as the Nortek Aquadopp-3D current meter and the Teledyne RDI Citadel CTD-ES probe. The profiler was successfully tested in the northeastern Black Sea during 2007–2009. By using the profiler, new data on the layered organization of the marine environment in the waters over the upper part of the continental slope were obtained. The temporal variability of the fine-scale structure of the acoustic backscatter at 2 MHz was interpreted along with biooptical and chemical data. The patchy patterns of the acoustic backscatter were associated with physical and biological processes such as the advection, propagation of submesoscale eddy, thermocline displacement, and diel migration of zooplankton. Further applications of the multidisciplinary moored profiler technology are discussed.