title: Parabolic equation modeling of high frequency acoustic transmission with an evolving sea surface.
abstract: The present paper examines the temporal evolution of acoustic fields by modeling forward propagation subject to sea surface dynamics with time scales of less than a second to tens of seconds. A time-evolving rough sea surface model is combined with a rough surface formulation of a parabolic equation model for predicting time-varying acoustic fields. Surface waves are generated from surface wave spectra, and stepped in time using a Runge-Kutta integration technique applied to linear evolution equations. This evolving, range-dependent surface information is combined with other environmental parameters and input to the acoustic model, giving an approximation of the time-varying acoustic field. The wide-angle parabolic equation model manages the rough sea surfaces by molding them into the boundary conditions for calculations of the near-surface acoustic field. This merged acoustic model is validated using concurrently-collected acoustic and environmental information, including surface wave spectra. Data to model comparisons demonstrate that the model is able to approximate the ensemble-averaged acoustic intensity at ranges of about a kilometer for acoustic signals of around 15 kHz. Furthermore, the model is shown to capture variations due to surface fluctuations occurring over time scales of less than a second to tens of seconds.
authors.affiliation: College of Earth, Ocean and Environment, University of Delaware, Newark, Delaware 19716, USA. sennejm@me.com
authors.forename: J
authors.initials: J
authors.lastname: Senne
authors.forename: A
authors.initials: A
authors.lastname: Song
authors.forename: M
authors.initials: M
authors.lastname: Badiey
authors.forename: K B
authors.initials: KB
authors.lastname: Smith
mesh_terms: D000162:Acoustics; D000465:Algorithms; D004735:Energy Transfer; D005583:Fourier Analysis; D008962:Models, Theoretical; D009038:Motion; D009792:Oceans and Seas; D011312:Pressure; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012815:Signal Processing, Computer-Assisted; D013016:Sound; D013018:Sound Spectrography; D013499:Surface Properties; D013997:Time Factors; D014867:Water; D014872:Water Movements
chemical_list: D014867:Water