A method of data analysis using 200 Hz ocean acoustic tomography system

Japan Marine Science and Technology Center (JAMSTEC) and Oki Electric Industry Co., have been developing the ocean acoustic tomography (OAT) system since 1989. JAMSTEC observed 3D temperature distributions in the Kuroshio Extension area by using this OAT system from July to September 1997. This paper describes the data analysis method used in this system and the results of this experiment. The observed data (i.e., the acoustic arrival time between each transceiver) were corrected using GPS-clock. Then, the corresponding ray arrival times in every measurements were tracked and identified with acoustic eigenrays calculated in the reference sound speed field. Perturbations of sound speed between estimation and reference fields were modeled using empirical orthogonal functions in the vertical direction and trigonometric functions in the horizontal direction. The results indicate the maximum predicted sound speed uncertainty over 1.2 m/sec.