Features of low-frequency pulse signals propagation through a vortex structure in the Japan Sea in winter conditions

Abstract

The results of the experiment done in the Japan Sea in March 2016 on the 194 kilometer long acoustic track are discussed. The most complicated case of the impulse wideband pseudo-random signals distribution from a shelf into a deep sea crossing the eddy is investigated. The analysis of the experimentally achieved impulse responses showed that the maximal first arrival detected in all measurements points has a good correlation with the calculations. The impulses propagated in the near-surface sound channel on a shortest range at angles close to zero are received first on the studied receiving horizon. For the case of the low frequency impulse signals distribution with small sliding angles through the eddy structure it is shown that ray trajectories do not take any significant changes, because the eddy influence have minor effect on the time structure of the impulse response formation on all the track. This fact allowed adapting widely known software for the acoustic field calculations RAY for the experiment conditions. The methodic of the average sound speed on a track calculation using data from satellite monitoring of the surface temperature is proposed. The methodic allows counting on successful application of the achieved results in the tasks of the acoustic rangefinding and navigation.