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1

Internal waves on a shelf

Serebryany A.

Hydroacoustics

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2014

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Vol. 17

187--198

EN

The paper considers the contemporary review of internal waves on a shelf based on thirty year’s experience of studying internal waves in Russian Seas. The frequency spectra of internal waves are presented and analyzed in shallow-water seas, with those waves being generated by different sources. A strong variability in the spectra differs from the Gurret-Munk one. The main processes which are enumerated lead to the generation of intense internal waves on a shelf. The characteristic features of the observed waves are described, including those of the second mode. Wide possibilities of the acoustic Doppler current profiler (ADCP) are demonstrated for studying internal waves in a sea.

2

Local acoustic tomography on shelf of the Black Sea

Goncharov V., Kuryanov B., Serebryany A.

Hydroacoustics

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2013

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Vol. 16

67--76

EN

Using self-contained acoustic buoys developed at the Shirshov Institute of Oceanology, experiments were performed to verify the possibility of acoustic tomography in a local region of a shallow-water sea. In the experiments carried out in October 2010 on shelf of the Black Sea, compound phase-manipulated signals are transmitted and the time responses of the medium are measured using three bottom-moored receiving and transmitting transducers separated by 1-km distance. The results of reconstructing the sound and current velocities are compared with the data of independent measurements made by set of standard oceanographic instruments (ADCP, CTD sounds, etc.).

3

Ambient noise induced by large-amplitude internal waves in the ocean

Serebryany A., Aredov A., Okhrimenko N.

Hydroacoustics

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2009

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Vol. 12

209-216

EN

Experimental data on the ambient noise generated by large-amplitude internal waves in the ocean are considered. The data are obtained by us during oceanic expeditions in the Indian Ocean and South China Sea. In both cases the generation of noise was caused by solitary internal waves with 50-m amplitudes. The internal waves were accompanied by strong orbital currents (up to 1.5 m/s) which created intense convergence with choppy surface waves at the sea surface. Simultaneous observations of internal waves and parameters of the ambient noise were carried out from a drifting vessel during calm weather. In both cases, the increase in the level of the ambient noise coincided with the passages of internal waves. The analysis of experimental data and the data of numerically modeling are presented.

4

Acoustical observation of internal waves on the shelf of the Black Sea

Mikryukov A., Popov O., Serebryany A.

Hydroacoustics

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2009

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Vol. 12

153-158

EN

In October, 2007, the Acoustics Institute performed complex acoustical and oceanological studies on a fixed experimental path in the Black Sea, near the Golubaya Bay. Sound signal with linear frequency modulation were used in the experiment. The processing of the experimental records consisted in computing the envelope of the correlation function of the received and transmitted signals and the time dependence of the correlation maxima. A characteristic change in arrival times of the rays is observed for the period of the income of cold near-bottom waters on the path. The quasi-harmonic variation in the arrival times of the ray groups allows one to correctly define the parameters of short-period internal waves accompanying the bore.

5

Propagation of pulsed sound signals on a shelf of free tidal sea: effects from coastal eddies and internal waves

Mikryukov A., Popov O., Serebryany A.

Hydroacoustics

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2008

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Vol. 11

279-288

EN

A long term experiment on studying fluctuations of the parameters of pulsed sound signals in a shallow sea was carried out in the region of the northeastern coast of the Black sea in autumn, 2004. the data were collected on a 1.2-km fixed propagation pathat a 2-km distance from the coastline. During the entire experimentation, observations of temperature fluctuations near the receiving point were performed by the using the line temperature sensor. Fluctuations of the shape, energy and propagation time of the pulsed signals were studied. an attempt of their relation to the hydrodynamic processes on the shelf was taken. The change in the shape and the energy levelof the signal was analyzed for the moment of passing the anticyclonic topographic eddy over the coastal zone. It was shown that the fluctuations of the propagation time were sometimes as high as 17.6 ms. An enhanceof the short-period acoustic fluctuations accompanying the internsification of the internal waves was observed.