Influence of Oceanic Synoptic Eddies on the Duration of Modal Acoustic Pulses

We consider the problem of scattering of the modal acoustic pulses from synoptic eddies with allowance for the influence of the field of internal waves. The ray formalism in terms of the action–angle variables is used. The synoptic-eddy induced distortion of the sound-speed profile is shown to enhance the scattering of certain ray bundles from internal waves. The formulas allowing one to identify the modal pulses corresponding to such ray bundles are derived. These pulses differ from the other ones by increased duration. This fact can be used for obtaining additional information during acoustic tomography. The model of the underwater acoustic channel in the Sea of Japan is considered as an example.