1000-km range 2 dimensional ocean acoustic tomography near Japan

1000-km range (621-km) two-dimensional ocean acoustic tomography (OAT) was conducted in the northwestern Pacific near Japan. A low frequency acoustic source (200 Hz) was moored just below the sound channel. Arrival signals from the upper direction and the lower one were separated by a beam forming technique. The stochastic inverse method was applied to the estimation of the sound speed perturbation. The expansion functions for horizontal and vertical direction were rectangular functions and empirical orthogonal functions (EOFs) respectively. The correlation of the sound speed anomaly was also included in the analysis. The results show that the characteristic pattern of cold-core rings observed in the temperature field with XBT was reproduced by the objective analysis process and the parameters.