Investigation of Acoustic Wavefield Dynamics in Quasi-Realistic Ocean Environments

• Main Author: Wolfson, Michael A
• Other Authors: WASHINGTON STATE UNIV PULLMAN DEPT OF PHYSICS
• Format: Text
• Language: English
• Published: 1998
• Subjects: Physical and Dynamic Oceanography; Acoustics; *ACOUSTIC FIELDS; *ACOUSTIC WAVES; *MATHEMATICAL MODELS; *NORTH PACIFIC OCEAN; *PREDICTIONS; *RAY TRACING; *THREE DIMENSIONAL; ACOUSTIC REFRACTION; ACOUSTIC SCATTERING; ACOUSTIC VELOCITY; CARTESIAN COORDINATES; INTERNAL WAVES; MOMENTUM; ROSSBY WAVES; SOUND TRANSMISSION; SPECULAR REFLECTION; TRAVEL TIME; *WAVEFIELD PREDICTABILITY; *REFRACTIVE SCATTERING; HELMOLTZ EQUATION; *ACOUSTIC RAY TRACE NUMERICAL MODEL; MESOSCALE STRUCTURE; ACOUSTIC RAYS; Arctic; Pacific; Alaska
• Online Access: http://www.dtic.mil/docs/citations/ADA552544; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA552544

Our long-term goal is to provide a more complete understanding of the forward propagation of acoustic pulses in range-dependent deep ocean environments at multi-megameter range scales. The objective of this project is to understand the limits of wavefield predictability in ocean environments where refractive scattering is the dominant physical process controlling the dynamics of the wavefield. The canonical scenario is long-range acoustic transmissions along the ocean waveguide, which has sound speed fluctuations due to oceanic processes characterized by linear Rossby waves and internal waves. The technical approach involved the development of a three-dimensional ocean acoustic ray trace numerical model associated with the solution of the one-way Helmoltz equation. The boundary conditions are specular reflection at the surface, open in the horizontal, and open on the bottom. A Cartesian coordinate system is used, and no account is taken for the sphericity of the Earth. A Hamiltonian prescription is facilitated, and besides the standard ray quantities (i.e., depth, cross-range, vertical momentum, horizontal momentum, and travel time), the model also solves for the elements of the stability matrix M. The three-dimensional ray model has been completed and simulations have been performed on the Cray T3E supercomputer at the Arctic Region Supercomputing Center at the University of Alaska. The simulations have used parameters for mesoscale structure that are relevant to the eastern North Pacific ocean, where the North Pacific Acoustic Laboratory (NPAL) experiment is being conducted. See also ADM002252.