ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

2aAO8. Acoustic footprints of an interthermocline eddy: Field experiment and numerical simulations.

Dmitry Yu. Mikhin

Dmitry L. Aleynik

Sergey V. Burenkov

Yury A. Chepurin

Viktor G. Selivanov

Sergey Ya. Molchanov

P. P. Shirshov Oceanogr. Inst. of the Russian Acad. Sci., Moscow 117851, Russia

Oleg A. Godin

NOAA/Atlantic Oceanogr. and Meteorol. Lab., Miami, FL 33149

A moving ship tomography experiment (MOST) was carried out in the western Mediterranean basin in 1994. Six moored transceivers deployed in the area by IfM (Kiel, Germany), IFREMER (Brest, France), and WHOI (Woods Hole, USA), in the framework of the THETIS-2 project, were utilized as wide-band sound sources for the MOST. An interthermocline eddy with cold core was found during the MOST. Detailed CTD surveys were performed along several sections of the eddy. In the horizontal, it was close to an ellipse with axes of 25 and 40 nm. The sound-speed difference at given depth inside and outside the eddy was up to 2 m/s. Within the eddy core the sound-speed gradient was an order of magnitude less than in surrounding waters. Acoustic signals from the transceivers were recorded at 16 points within and around the eddy in order to study feasibility of reconstruction of mesoscale inhomogeneities of this type by acoustic tomography means. A technique of coherent signal processing used made it possible to resolve multiple eigenray arrivals from four transceivers at each point of observations. Results of mathematical modeling of the acoustic effects of the eddy and their comparison with the experimental data will be reported. [Work supported by ISF and INTAS.] [sup a)]On leave from P. P. Shirshov Oceanography Institute, Moscow.