Effects on acoustics caused by ocean solitons, Part A: Oceanography

Abstract

Our work addresses the link between internal solitary waves and acoustics. The location of the study is in the Yellow Sea south of the Shandong peninsula. Previously in this region, we have performed internal solitary wave generation and propagation simulations with the Lamb nonhydrostatic model [K. Lamb, Numerical experiments of internal waves generated by strong tidal flow across a finite amplitude bank edge, J. Geophys. Res. 99 (c1) (1994) 848–864; A. Warn-Varnas, S.A. Chin-Bing, D.B. King, J.A. Hawkins, K.G. Lamb, M. Teixeira, Yellow Sea ocean-acoustic solitary wave modeling studies, J. Geophys. Res. 110 (2005) C08001, doi:10.1029/2004JC002801]. The model parameters were tuned to SAR data. Here, we consider variations of solitary wave characteristics in parameter space. We introduce scaling parameters for a two-layer analogue configuration. This analogue is applied to predicted numerical solutions with the full nonlinear nonhydrostatic Lamb model in the first of the above-mentioned references. Variations of density difference across the pycnocline, tidal forcing and topographic height are considered. Characteristics of solitary waves are analyzed as the parameters deviate from a tuned case to data. Changes of solitary wave functional form, amplitude, wavelength, and phase speed are tracked. We consider oceanographic and acoustical parameters that describe the physical ocean–acoustic environment and its associated variability. For certain source, receiver, and acoustical frequency configurations, a redistribution of acoustical energy to higher modes can occur and result in acoustical intensity loss in the presence of solitary wave trains [A. Warn-Varnas, S.A. Chin-Bing, D.B. King, J. A. Hawkins, K.G. Lamb, M. Teixeira, Yellow Sea internal solitary wave variability, in: N.G. Pace, Finn B. Jensen (Eds.), Impact of Littoral Environmental Variability on Acoustic Predictions and Sonar Performance, Kluwer Academic Publishers, Dordrecht, The Netherlands, 2002]. This will be considered in part B.