We have performed detailed analysis of evolving coupling behavior in a packet as it moves through the ocean. It was shown that the relative phasing between dominant modes largely controls mode coupling and signal fluctuations caused by an entire packet, comparable to single-wave behavior, despite the added complexity of the problem. The net gain is dependent on packet position relative to the source and source depth. These fluctuations are controlled primarily by the relative phasings of the dominant modes of the acoustic field as it first encounters the soliton packet. The signal reaching a receiver 33 m from a source is a strong function of the position of an intervening internal wave packet.
Propagation is adiabatic except in the packet.
Figures 4 and 5 show the level of energy in each acoustic mode between the source and the receiver. The modes are attenuated by bottom interactions at different rates. Since mode 1 propagates effectively, the loss of mode 1 energy to other modes in the case leads to signal loss at 33 km. Conversely, it is useful to compare the nonlinear-wave effects to other possible effects. A single nonlinear wave packet of 10 to 15 m displacement amplitude gives signal fluctuations of order 10 dB at 33 km range.