Konstantin A. Naugolnykh
Environ. Technol. Lab., Boulder, CO 80303
Igor B. Esipov
N. Andreyev Acoust. Inst., Moscow 117036, Russia
Parametric arrays launched by P. J. Westervelt as a result of an investigation of nonscattering of sound by sound [P. J. Westervelt, J. Acoust. Soc. Am. 35, 535--537 (1963)], have become familiar in the practice of marine research. The narrow beam of a wide frequency band parametric signal in the low-frequency range makes an attractive parametric array application for ocean sensing on a long-range acoustic pathway. Results of an experimental application of a high power narrow beam parametric array in a variety of environmental ocean conditions, that is, shallow water, long-range (up to 1000 km) signal propagation, and synoptic ocean eddy remote sounding, are considered in this paper. This space pattern of the parametric antenna field is shown to be essentially changed with the direction of the ocean eddy probing. Horizontal refraction occurs when a parametric signal passes through the eddy. This shows the possibility of a long distance tomographic analysis of mesoscale environment patterns of the ocean by a high-directed parametric array. The problem of parametric array application on elongated pathways in the ocean is discussed, the advantage of the parametric array with respect of a conventional one in the ocean waveguide is considered also. [Work supported by ISF grant MH 1300 and RFFI grant 95-02-06353a.]