A concept for remote acoustic monitoring of solitons generated in straits

Abstract

A search algorithm for resonance anomalies (SARA) has been developed to predict possible resonance frequencies of shallow-water soliton packets as they travel through straits. The algorithm relies on characteristics that accompany large losses due to acoustic wave-soliton interactions: (a) acoustic mode conversions; (b) large signal losses within a narrow band of acoustic frequencies; and, (c) large transmission losses due to strong couplings between lower-order propagation modes and higher-order, bottom-interacting modes. The SARA algorithm has been verified using oceanographic data from the Strait of Messina. As a remote acoustic sensor, the SARA algorithm could be used in an ‘‘inverse mode’’ to predict key oceanographic parameters (e.g., predominant horizontal spatial wave numbers and travel speeds) of those soliton packets that produce large acoustic losses. The parameters would initialize a primitive shallow-water soliton model that generates soliton simulations. The SARA algorithm could be used in a forward fashion to validate the soliton simulations. The concept exploits the unique sloping bathymetry of straits, where natural mode stripping can occur around the sills that generate the solitons. Details will be discussed and computer simulations will be presented that illustrate the feasibility of the approach. [Work supported by ONR/NRL and by a High Performance Computing DoD grant.]