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  • Author or Editor: Emil V. Stanev x
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Nickolay H. Rachev and Emil V. Stanev


The enclosed boundaries and small scales of some seas lead to the formation of specific physical balances, which motivates the oceanographic interest in studying the dynamics of semienclosed ocean basins. The focus in the paper is on the specific appearances of eddy processes when the basin scales and the ones of the topographic features are comparable with the baroclinic radius of deformation. The Black Sea is used as a test basin. Eddy variability is analyzed using simulation results and compared with existing observations. The Bryan–Cox model with horizontal resolution Δφ = 1/10° and Δλ = 1/6° is forced with annual-mean wind stress data. Buoyancy flux at the sea surface is proportional to the deviation of the model density from the annual-mean climatological data. Sensitivity studies on different forcing and on the topographic control are carried out. Synoptic periods are estimated to be about 0.5 yr. Eddies form in the eastern Black Sea and propagate westward with a speed of about 3 cm s−1. The narrow section of the Black Sea, between the Crimea Peninsula and the Turkish coast, strongly affects eddy propagation. Dissipation increases in the western basin, where eddies slow down and their scales become small. This process is dependent on topography, which is dominated by a large shelf area in the western basin. Eddy kinetic energy exceeds the kinetic energy of the mean motion over large areas. Energy transfer between external and internal modes shows that the topographic control and the nonlinear transfer almost compensate each other. Energy spectra indicate that an inverse cascade may occur.

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Andrey Pleskachevsky, Mikhail Dobrynin, Alexander V. Babanin, Heinz Günther, and Emil Stanev


This paper studies the impact of the surface waves on the turbulent mixing. The satellite observations of suspended particulate matter (SPM) at the ocean surface as an indicator of turbulent quantities of the flow are used. In a water column, SPM builds a vertical profile depending on settling velocities of the particles and on vertical mixing processes; thus, SPM is a perfect marker to study the turbulent quantities of the flow. Satellite observations in the North Sea show that surface SPM concentrations, in locations of its deposition, grow rapidly and build plume-shaped, long (many kilometers) uninterrupted and consistent structures during a storm. Also, satellites reveal that SPM rapidly sinks to the seabed after the storm peak has passed and wave height decreases (i.e., in the absence of strong turbulence).

The nonbreaking wave-induced turbulence has been discussed, parameterized, and implemented into an equation of evolution of turbulent kinetic energy (TKE) in the frame of mean-flow concept, which can be used in existing circulation models. The ratio between dissipated and total wave energy is used to describe the influence of wave damping on the mean flow. The numerical tests reproduce experiments in a wave tank very well and are supported by observations of SPM in the North Sea. Their results show that the motion of an individual nonbreaking wave includes turbulent fluctuations if the critical Reynolds number for wave motion is exceeded, independent of the presence of currents due to wind or tides. These fluctuations can produce high diffusivity and strongly influence mixing in the upper water layer of the ocean.

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