In December 2003, a hydrographic section across the Drake Passage was carried out by R/V Aka-demik Sergei Vavilov from King George Island to Tierra del Fuego with a Seabird 911 and lowered Doppler current (ADCP) profilers. A total of 25 stations were occupied across the passage from the surface to the bottom. The geostrophic water transport by the Antarctic Circumpolar Current (ACC) above the bottom reference level is estimated at 111 Sv (1 Sv = 10⁶ m³/s), while the transport above the 3000 dbar reference level is equal to 97 Sv. These values are close to the smallest ones in the record of measurements of water transport through the Drake Passage since 1975. The geostrophic velocities are compared with the LADCP and shipborne ADCP measurements.

This paper presents a discussion on recent data obtained from combined analysis of remote sensing (satellite) and in situ observations for studying submesoscale dynamics in the White Sea associated with internal waves, eddies and frontal features. Multi-year complex monitoring revealed the widespread occurrence of short-period internal waves in the White Sea and allowed to obtain their statistical properties. Main characteristics of submesoscale eddies in the White Sea were also mapped. Statistical analysis shows that main eddy activity areas are found in the vicinity of hydrological fronts. The results of satellite IR data processing provide statistical description of mean sea surface temperature gradient and characteristics of major fronts in the White Sea on the monthly and decadal scales. Field observations in areas with pronounced vertical stratification revealed strong dynamics of eddies in the upper layer and significant variability of characteristics and position of the frontal zones within a tidal cycle over irregular topography. The performed analysis strongly suggests that in-depth understanding of submesoscale variability of hydrophysical fields in the White Sea under the influence of the tidal flow should certainly capitalize on synergy of satellite and in situ observations combined with modeling. Perspectives of such a research for the White Sea are discussed and outlined.

This paper examines the onset mechanism of self-oscillations of mast hoisting gears (MHG) related to their non-linear hydrodynamic characteristics as well as the action of external periodic forces on this self-oscillating system caused by the vortex separation similar to the Karman vortex street type. MHG oscillation equations under determinated and random hydrodynamic actions are presented. Provision for numerical determination at initial design stages of unsteady forces acting on MHG is demonstrated and comparison with experimental data is provided. On the basis of averaging method relationships were obtained for the determination of amplitudes of steady-state oscillations under the action of external periodic forces on the self-oscillating system due to vortex separation. When the coefficient of side force due to attack angle is approximated by the third-order polynomial, this relationship will be a cubic equation relative to the squared steady-state amplitude but when the same is approximated by the fifth-order polynomial, this relationship will be a quintic equation. Stability conditions of steady-state oscillation modes were obtained for various options of approximation of MHG hydrodynamic characteristics. It is shown that in the autonomous system with a cubic approximation of the side force versus attack angle relationship, amplitudes increase infinitely, if instability appears. To eliminate this effect the fifth-order polynomial approximation of the side force versus at-tack angle relationship is required. With an actual MHG structure being taken as an example, MHG amplitude-frequency characteristics in the resonant area were plotted using the above-mentioned relationships.

The paper reviews and analyzes few-parameters optical models of water inherent optical properties (IOPs). These models are classified as correlational and structural models. Correlational models establish relations either between values of a single IOP at different wavelengths (spectral models) or between values of several IOPs at the same wavelength. The correlations between attenuation, scattering and backscattering coefficients at 550 nm were shown to be valid for the majority of open and coastal regions of the World Ocean. In particular, they can be used to compute parameters of under-water imaging systems operating in this spectral range. Correlational models make it possible to determine the values of IOP for the whole visual spectrum on the basis of the value of the attenuation coefficient at 550 nm. The structural models describe IOPs in terms of concentrations of optically active matters (OAM): phytoplankton, sediment and colored dissolved organic matter. We show that these models are very diverse and often mutually contradictory; their domain of application is limited and their accuracy is often unknown. Nevertheless, they make it possible to estimate a range of possible IOP variation for given OAM concentrations.

The main task in the course of hydraulic system of ship power plants construction is to suppress flu-id-borne noise. One way to get around this problem is the application of the pressure pulsation dampener. The dampener is the device that filters acoustics pulsation in working fluid and scatters their energy. However the existing methods of pressure pulsation dampener design do not take into ac-count the processes of noise formation due the vortexes on its elements. This fact causes the significant decline of the dampener efficiency under the rise of the flow rate conditions. In this work the new method of pressure pulsation dampener design is presented. The main difference of developed method from traditional ones is the modeling of vortex flux in the diffuser of dampener central duct and fluid-borne nose occurring in such condition. The use of the method allows to define the process pattern of unsteady flux generation in the diffuser. It has been shown that the field of the maximum of the root-mean-square pressure pulsation located near the wall at the inlet part of the dampener diffuser. The frequency vs pressure pulsation in the diffuser curve has been simulated. The developed design method of the pressure pulsation dampener allowed to achieve mean value of insertion losses coefficients equal to 10.6 in the frequency band of 5 Hz to 1 000 Hz under the velocity of the working fluid up to 30 m/s.

The features of practical implementation of the holographic method of the acoustic field recovery in the space of the waveguide, which is the method of the matched field processing, as well as the theoretical basis of the method are considered in the article. The paper shows the relationship of characteristics of restored acoustic field of sound source with the complex transfer function of the wave-guide, which is determined on the basis of the solution of the wave equation. A simple recovery source field by applying computational procedures of calculating the transfer characteristics of the waveguide by a finite difference method for the explicit calculation scheme is noted. The results of computational experiments on the study of the effectiveness of the method in the conditions of an inhomogeneous underwater environment are presented. Each numerical experiment consisted of two stages: calculation of the hologram field of a point source of a sound and subsequent recovery of the acoustic field. For computational experiments a shallow waveguide with a flat bottom and with a positive acoustic refraction of the rays from the surface to the bottom was selected. In the paper three simplified models of inhomogeneous underwater environment are considered: with small-scale turbulence, with internal wave, with a layered structure of the vertical distribution of sound velocity. It is shown that the unaccounted in homogeneities of the velocity of sound along the length of the waveguide have a material adverse effect on the efficiency of recovery of the field of a source of a sound by holographic method. This effect can be reduced by clarifying the parameters of the environment along the waveguide.