A study of hybrid and chaotic long-range propagation in a double sound channel environment

This paper presents the results of the analysis of long range propagation ( similar to 200 km) in a range-dependent environment. The propagation medium is characterized by two deep sound channels. The range dependence enables energy transfer between the channels and leads to a mismatch between real d ata and ray predictions. To explain this mismatch, an analysis of hybrid ra y propagation is presented. This analysis is completed by an interpretation in terms of chaos. This chaos is quantified in the particular case of the Bay of Biscay environment. This paper puts forward that mesoscale perturbat ions, such as the Mediterranean outflow in the North Atlantic, can affect l ong-range propagation. However, it shows that the ray theory remains reliab le for a propagation range of several hundred kilometers.