The most important results

Laboratory of geophysical boundary layers

Figure 1.1 – Nonlinear three-wave interaction.

Description of the evolution of a single internal wave and factors affecting the rate of its decay

In experiments with the passage of an internal wave in a channel, the evolution of the process is described and quantitative characteristics of the transition time from the co-directional wave motion to the synchronization conditions and nonlinear 3-wave interaction are obtained. With the help of wavelet analysis, the picture of energy transfer from the wave of forcing and the long wave to the resulting internal wave is obtained (Fig. 1.). The influence of variations in the boundary conditions on the evolution of a single wave in a channel is studied.

Estimates of the applicability of spectral models for describing the frequency of extremely high wind waves

Figure 1.2 – Repeatability of wave surface deviations from the mean level: 1 – calculations from the reproduced nonlinear model; 2 – calculations on the ensemble of linear waves.

It is shown that the results of the numerical simulation of wind waves essentially depend on the fine details of the initial conditions. It is proved that statistically ensured results should be obtained by ensemble modeling. Popular approaches based on spectral representations ignore many real properties of surface waves.

Given the exact conservation of energy, the wave spectra calculated in different versions turned out to be different. Thus, the evolution of the spectrum is determined not by fixed resonance combinations of modes.

The repeatability of surface deviations from the mean level is shown in Fig. 1.2. Curve 2 shows a strict symmetry of perturbations relative to the mean level. Curve 1 confirms that the probability of positive disturbances far exceeds the probability of negative perturbations, in particular, the heights of the wave crests are much larger than the depths of the wave soles, i.e. Nonlinear waves are more pointed than linear ones. This, firstly, means that each mode approaches the Stokes mode, and, secondly, reflects the effect of focusing of energy when the wave combs coincide.

Solution of the problem of the gas hydrate-gas phase transition

Figure 1.3 – Dependence of temperature in the center of the sensor on the radius of the vessel.

Based on the original method of numerical modeling of thermobaric processes (including phase transformations of methane-methane hydrate) occurring after the instantaneous inclusion of a linear heat source in a cylindrical vessel filled with a porous mineral medium with methane hydrates, water and methane gas, according to the parameters measured during the experiment, calculate the porosity values, as well as the water and gas saturation of the medium and the hydration saturation of the medium.

The fixed flattening of the experimental temperature dependence of the temperature T in the center of the sensor («needle») from the logarithm of the time lg(t) is explained not by an increase in the thermal conductivity of the medium or by the influence of the isothermal vessel body, but by the exothermic nature of the hydrate dissociation reaction (Fig. 1.3). The results of numerical simulation allow us to explain a number of experimental features of the thermal regime of the test medium.

Regularities of sub-mesoscale processes and phenomena in the tidal arctic sea (on the example of the White Sea)

Figure 1.4 – Manifestations of short-period internal waves by radar data of 2010. The positions of the leading wave crests in packets are shown. а – all data, б – regular wave packets from the throat, в – frontal wave packets, г – irregular waves. The red lines indicate the positions of the front lines (on average for the season).

A scientific concept is developed that sub-mesoscale structures are formed under the influence of processes different in physical nature and collectively in the sea area form a single system that is a transitional link from mesoscale (tidal) movements to the microstructure; for their research, a special methodology should be used that combines observations and cumulative analysis of large-scale remote and frequent contact measurements. Methods of investigation and complex analysis of fine-structure and sub-mesoscale processes and phenomena in the water area of the tidal sea are proposed on the basis of a combination of heterogeneous satellite data and time-honored observations at oceanographic sites that allow monitoring in the entire sea.

The existence of previously unknown links and relationships, in particular, between the synoptic and mesoscale dynamics of the main frontal sections in the White Sea and the distribution of short-period internal waves (Fig. 1.4) and sub-mesoscale whirls and between the distribution of sub-mesoscale phenomena in the water area and the intensity of horizontal and vertical turbulent exchange is proved.