Mid Frequency Bottom-Interacting Sound Propagation and Reverberation in the Baltic

ABSTRACT

The experiment BAROC (Baltic Acoustics on Rocky Outcrops) was performed in May 2002. Analysis and modelling of part of the received data are reported here, concerning transmission loss and reverberation in a shallow-water area south of Stockholm. LFM pulses were transmitted in two directions with frequency content between 500 and 5500 Hz. In both directions a clear sound channel was observed, for which the optimum propagation frequency was about 4 kHz. Strong bottom reverberation was measured. A ray-trace model has been used as forward model for inversion of bottom parameters with a genetic algorithm. The inversion results were subsequently verified with a parabolic-equation model, and they were used to assess the level of reverberation.