Site: Pacific Oceanological Institute
43 Baltiskaya St.
Vladivostok, 690041, Russia
Phone: (4232) 311400
Fax: (4232) 312573

Date Visited: October 23,1995

WTEC Attendees:

H. B. Ali (report author), R. Blidberg, S. Chechin, M. J. DeHaemer, L. Gentry, J. Moniz, J.B. Mooney, D. Walsh

Hosts:

Gennady Y. Voloshin

Deputy Director.
Email: poi@stv.iasnet.com

E. F. Orlov
Renat D. Medzhitov

Head, Sea Technology Research Division

Vladimir A. Shchurov

Head, Lab. of Ocean Noise

Dr. Shulskov
Lev F. Bondar

Chief, Laboratory of Acoustic Sounding of Ocean

BACKGROUND

The Pacific Oceanological Institute (POI) is the major institution in FEB RAS. It was founded in 1973; it presently has a staff of over 600 people, including approximately 270 scientists, of whom 160 are professors and doctors of science. As part of their multidisciplinary marine program, the researchers of the institute carry out experiments in various geographic areas: the Pacific Ocean, the Sea of Okhotsk, the Bering Sea, the Sea of Japan, the East China Sea, the Philippine Sea, the South China Sea, etc. An offshore experimental station on Popov Island near Vladivostok provides facilities for operations in the littoral zone.

RESEARCH AND DEVELOPMENT ACTIVITIES

POI focuses on the following research areas:

INDIVIDUAL REPORTS

Multidimensional Signal Analysis

Professor Gennady Y. Voloshin, deputy director of POI, provided a brief overview of the work the institute. He emphasized the work done in the area of multidimensional signal analysis. In particular, he stated that they perform correlation and spectral analysis using a method which is superior to the FFT methods -- viz., their method is faster than FFT methods and, in addition, gives exact correspondence between the spectral density and correlation even for discrete series (unlike the FFT).

Low Frequency Acoustics

Dr. E. F. Orlov discussed low-frequency acoustics (one to "hundreds" of Hz). He emphasized the use of "acoustic interferometry" to investigate the spatial coherence structure of low-frequency acoustic fields in the ocean. Broadband acoustic energy propagating in an ocean waveguide may exhibit a two-dimensional space-frequency spectrum determined by the modal interference of the waveguide modes. Since the modal interference pattern is sensitive to relatively small fluctuations in the oceanographic parameters (index of refraction), changes in the pattern may be used to infer the properties of the medium along the path of propagation. Dr. Orlov suggested that the use of interference phase tomography is a promising way to study the characteristics of the sea bottom in shallow water, on the continental slope, and in deep-sea areas.

Electric and Magnetic Fields in Ocean Currents and Waves

Dr. Renat D. Medzhitov, head of the Sea Technology Research Division, discussed the use of electric and magnetic fields to study ocean properties. In particular, he is interested in electromagnetic fields induced by oceanic currents and by surface and internal waves. The investigation is not confined to theoretical work but includes development of instrumentation for this purpose (e.g., towed electromagnetic sensors). Among the examples and possible applications, he mentioned the use of virtual current distributions obtained from separated electrodes to determine the water distribution in the Bering Sea.

Micro- and Mesoscale Processes

Dr. Shulskov reviewed their efforts in monitoring micro- and mesoscale processes in the northern Pacific. These processes, often referred to as the ocean "weather," play a significant role in the transfer of ocean properties and substances. They affect not only biological activity and the distribution of marine organisms but also pertinent oceanographic parameters, such as the propagation of sound. Consequently, acoustic sounding is an effective means to remotely sense micro- and mesoscale processes and in many ways is preferable to conventional monitoring methods -- including drifting ships, satellites, stationary and floating buoys, etc. The acoustic method is characterized by high spatial resolution, increased information content, and continuous measurements while underway. The scattering of acoustic energy by gas bubbles, microorganisms, and other microscale hydrophysical nonuniformities can be used to observe frontal zones, eddies, jet streams, intrusion, the processes of vertical mixing in the upper ocean layers, etc.

Shulskov presented some of the results of their measurements from the research vessel Academik M. A. Lavrentyev using a multifrequency (broadband) acoustic source along with towed temperature and salinity sensors. He proposed the use of well-equipped fishing vessels to perform large scale systematic measurements in the northwest section of the Pacific Ocean and its marginal seas. This, he suggested, would result in observations of quality and quantity sufficient not only to provide a detailed picture of mesoscale physical and biological processes but also to predict them.

Scalar-Vector Analysis of Ambient Noise in Water

Dr. Vladimir A. Shchurov discussed investigations of ambient noise in deep and shallow water using the "scalar-vector" method. The method is based on the simultaneous measurement at a given point of the acoustic pressure field and three orthogonal components of the particle velocity of the medium. Combined processing of the four acoustical field components enables the computation of the energy flux density vector (Poynting Vector) and hence of the flow of ambient noise energy. The investigation of the motion of ambient noise energy has led to several important applications, including those discussed below.

Experimental systems based on the preceding concepts have been developed and used in both deep-water areas and coastal zones. These have included both bottom-moored and drifting buoy systems, operating over a frequency range from 1 to 1000 Hz, and at depths between 10 and 2000 meters. The Shchurov group has published its results in several English-language publications and is interested in joint work with other countries.

Analysis of the Variability of Underwater Acoustic Signals

Dr. Lev F. Bondar discussed his work on the variability of underwater acoustic signals. The nonhomogeneities of the sea, coupled with the dynamic properties of shallow water, create a complex acoustic environment in coastal areas. In straits, for example, they have measured daily variations in ambient noise ranging from 10 to 20 dB. As a result, they do not rely exclusively on acoustic monitoring methods but simultaneously measure hydrophysical parameters. They use a special monitoring station in the shelf zone, within 100 km of Vladivostok, equipped with hydrophones, geophones, and a vertical array of additional sensors to monitor such things as internal waves.

SUMMARY

The Pacific Oceanological Institute (POI) is the major institution in FEB RAS. It probably ranks first among research institutions in the former Soviet Union in the area of acoustics of the ocean, although its activities cover a much broader spectrum of ocean exploration disciplines. Results of their investigations, particularly in ambient noise, have been published in a number of places. However, it is not clear whether the significance of this work has been understood by U.S. and other researchers in the field.

The POI participates in various international projects devoted to ocean studies, including WOCE, WESTPAC, JGOFS, and others. They are eager for joint projects and patents, particularly with the United States.

REFERENCES

Ilyichev, V. I., and V. A. Shchurov. 1993. "The properties of the vertical and horizontal power flows of the underwater ambient noise." Natural Physical Source of Underwater Sound, pp. 93-109, Kluwer Academic Publishers, Netherlands.

Medzhitov, R. D. Handout, consisting of brief English descriptions of proposed joint studies, objectives of his research work, theoretical basis of his work, and some results.

Orlov, E. F. "Acoustic interferometry in the ocean." Unpublished 2-page description (in English).

Schchurov, V. A. 1994. "Abstract for a proposed joint project." Unpublished 1 1/2-page translation of proposed joint Russia-U.S. project to develop the "scalar-vector" passive acoustical system.

Schchurov, V. A. 1994. "An abstract for report 'the modern state of the scalar-vector measurements in underwater acoustics' (The Modern Experimental Achievements and Perspective Directions)." Unpublished 2-page summary.

Shchurov, V. A. 1991. "Coherent and diffusive fields of underwater acoustic ambient noise." Acoust. Soc. Am. 90, pp. 999-1001.

Shchurov, V. A. 1991. "The interaction of energy flows of underwater ambient noise and a local source." J. Acoust. Soc. Am. 90, pp. 1002-1004.

Schchurov, V. A.. "Acoustical drifting autonomous telemetric analogue system." Unpublished description and specifications (in English) of the ADATAS system.

Schchurov, V. A., V. I. Ilyichev, and V. P. Kuleshov. 1994. "The ambient noise energy motion in the near-surface layer in ocean wave-guide." Journal de Physique IV, vol. 4, C 5, pp. 1273-1276.

Schchurov, V. A., V. I. Ilyichev, and Yu. Khvorostov. 1992. "Ambient noise anisotropy in horizontal plane." 14th ICA, Beijing.

Shevtsov, V. P. "Monitoring of mesoscale processes in northern pacific." Unpublished 2-page description (in English).


Published: August 1996; WTEC Hyper-Librarian