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Application of Results

The experimental data collected in course of the present study will be used for comparative analysis of 3 approaches to the Ocean Acoustic Tomography, namely: Traditional (Moored) Tomography, Dynamic Tomography and Matched Field Tomography using multi-element arrays. The particular topics of research are:

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to complete 2D inversions for particular vertical slices along the propagation paths of the major THETIS-2 experiment; to carry out 3D inversion of the sound speed field in the whole Western Mediterranean basin; to compare the accuracy of Dynamic and Traditional Tomography Experiments in reconstructing the mean (range- and space-averaged) oceanographic parameters of the medium and their horizontal variability; to assimilate the data obtained via these 2 approaches and through the surveys with long vertical arrays;

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to continue the development of linear and non-linear full-field inversion techniques along the lines described in Sect. 2.2.4 and [20, Sub-task 3.2,]; to apply (and, if necessary, to adapt) the proposed algorithms to different tomographic problems, such as remote acoustic sensing of the Arctic basin;

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to perform range-independent and, possibly, 2D inversion of the data collected in Matched Field Experiments; the results will be balanced against those obtained for the same vertical slices in THETIS-2 and Dynamic Tomography experiments to reveal the gain from using multiple receivers in a single vertical slice;

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to study the potential of multi-element arrays moored in shallow water close to the coast for the goals of basin-scale monitoring (see Sect. 2.2.2.2.2);

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to reconstruct the 3D sound speed field in the Weddy area (Sect. 2.1.6) and to study the possibility of remote acoustic detection and monitoring of such inhomogeneities; using our CTD data and satellite images obtained by our colleagues Drs. C. Millot and J.-L. Fuda of COM-CNRS to study the current field in the Weddy, its drift and temporal evolution;

It is expected that the 3 methods considered possess mutually complementary points. The planned study based on real experimental data will lead to quantitative estimates of their performance under the same environmental conditions. It will reveal the best ways of intergating the different tomographic techniques and inversion methods in future routine observational systems.

The initial Work Programme of the present project submitted to INTAS in 1993 provided for 2-year research which included both field experiments on 3 different approaches to the Ocean Acoustic Tomography, and data inversion and comparison of the results. The project finally supported by INTAS included only the first part. The outcome of this investigation is presented in the current report. We plan to continue the study along the above mentioned lines. For this purpose we plan to apply for continuation of this project and hope that its second year, which originally was not approved, will really take place. The work will be also continued in the framework of domestic Russian project RFBR # 95-05-14616.

The scientific contacts and fruitful cooperation established between Russian and European partners in course of this project will be continued. The same team (with minor replacements) has submitted a research proposal to the Joint INTAS and RFBR Call of 1995. The proposal entitled ``A new, full-field approach to acoustic tomography of ocean currents in the coastal zone'' is devoted to acoustic monitoring of water fluxes between the Atlantic ocean and the Mediterranean through the Strait of Gibraltar. The application was approved for funding, the project reference number is INTAS-RFBR 95-1002.

One more area of planned collaboration is related with analysis of the collected CTD and IR data and further studies of the observed Weddy. The inhomogeneity surveyed during our trial proved to be an interesting mezoscale feature, which, to our present knowledge, has not been observed before in the area and season of the measurements. Its origin and life-span, as well as contribution of such eddies to the circulation processes in the Western Mediterranean basin should be studied. The work is carried on by the Russian oceanographic team (Drs. E. A. Plakhin, D. L. Aleynik with contribution from acousticians of P.P.Shirshov Institute) and our French colleagues Drs. C. Millot and J.-L. Fuda. On the first stage, the analysis of the in situ and remotely sensed data already collected about the Weddy will be finished. The results of the 2 methods will be compared to develop the optimal scenario of the future search. The second step will be to conduct a dedicated at-sea experiment to catch a new event of such inhomogeneity.


next up previous contents
Next: Management and Financial Information Up: Research Activities Previous: Summary of Results

Dmitry Mikhin
Sun Dec 8 11:32:03 GMT+0300 1996