Spatio-temporal variability of bottom reverberation striation pattern in shallow water

Abstract

Interference pattern of bottom reverberation can be a source of additional information about underwater environment. Over the last decade, the striations in bottom backscattered broadband signals in the time-frequency domain were observed in several short-term experiments (Goldhahn et al., 2008, Li et al., 2010). In our research, numerical simulations are carried out to analyze the long-term variability of bottom reverberation striation pattern in the presence of internal waves (IW), both background and solitary-like. Coherent normal mode reverberation model is applied. Backscattered chirp signals are selected from different directions by a bottom mounted horizontal array. Simulated striation patterns reveal frequency shifts that are dependent on bearing and IW type. This phenomenon can be used to monitor the spatio-temporal variability of IW. To increase the sensitivity of this approach, the time-reversal sound focusing on the seafloor is proposed. [Work supported by RFBR, 16-32-60194.]