Interaction Features of Internal Wave Breathers in a Stratified Ocean
Oscillating wave packets (breathers) are a significant part of the dynamics of internal gravity
waves in a stratified ocean. The formation of these waves can be provoked, in particular, by the decay
of long internal tidal waves. Breather interactions can significantly change the dynamics of the wave
fields. In the present study, a series of numerical experiments on the interaction of breathers in the
frameworks of the etalon equation of internal waves—the modified Korteweg–de Vries equation
(mKdV)—were conducted. Wave field extrema, spectra, and statistical moments up to the fourth
order were calculated.
In this paper for the explain of the mechanism of formation of smooth strips (slicks) on the sea surface under the action of internal waves are used the film of surface-active substances, attendees everywhere in the sea. Experimental data on the real characteristics of marine films of surface-active substances are used for the calculation of histograms of contrast in the spectrum of wind ripples in the centimeter range for various parameters of the internal wave and wind wave lengths within the "film" mechanism of the effects of internal waves on the spectrum of wind-generated waves. It is shown that the ripple in the wavelength range 2-3 cm contrast weakly depends on the parameters of the internal waves (although with increasing internal wave amplitude), and the average number of 6-7 dB. For greater lengths ripple contrast is strongly dependent on the ratio of the rate of flow of water particles in the internal waves to the phase velocity of the internal wave. This dispersion deviations from average contrast values around the average value, which indicates a strong variation of contrast in each case. Nevertheless, it can be concluded relatively low sensitivity of "film" mechanism of action internal waves on the sea surface to a particular type of surface-active substances.
Purpose: Numerical modeling of internal baroclinic disturbances of different shapes in a model lake with variable depth, analysis of velocity field of wave-induced current, especially in the near-bed layer.
Approach: The study is carried out with the use of numerical full nonlinear nonhydrostatic model for stratified fluid.
Findings: The full nonlinear numerical modeling of internal wave dynamics in a stratified lake is carried out. The calculated distributions of near-bed velocities are analyzed; the significance of 3D effects for the velocity fields is emphasized; the regions of maximal (where internal waves are the main driving factor for sediment resuspension and erosion processes on the bed) and minimal velocities are marked out.
Originality: The results are new and can have practical application for many applied problems, especially ecological and economical, concerned with the processes of propagation of natural and anthropogenic pollutions in natural basins and the investigation of water quality, as well as with influence upon engineering structures and sediment transport.
Properties of rogue waves in the basin of intermediate depth are discussed in comparison with known properties of rogue waves in deep waters. Based on observations of rogue waves in the ocean of intermediate depth we demonstrate that the modulational instability can still play a significant role in their formation for basins of 20m and larger depth. For basins of smaller depth, the influence of modulational instability is less probable. By using the rational solutions of the nonlinear Schrodinger equation (breathers), it is shown that the rogue wave packet becomes wider and contains more individual waves in intermediate rather than in deep waters, which is also confirmed by observations.
A method based on the spectral analysis of thermowave oscillations formed under the effect of radiation of lasers operated in a periodic pulsed mode is developed for investigating the state of the interface of multilayered systems. The method is based on high sensitivity of the shape of the oscillating component of the pyrometric signal to adhesion characteristics of the phase interface. The shape of the signal is quantitatively estimated using the correlation coefficient (for a film–interface system) and the transfer function (for multilayered specimens).