Shallow Water Propagation and Surface Reverberation Modeling

• Main Author: Deane, Grant B
• Other Authors: SCRIPPS INST OF OCEANOGRAPHY LA JOLLA CA MARINE PHYSICAL LAB
• Format: Text
• Language: English
• Published: 2013
• Subjects: Physical and Dynamic Oceanography; Acoustics; *ACOUSTIC SCATTERING; *AMBIENT NOISE; *OCEAN SURFACE; *REVERBERATION; *SHALLOW WATER; *UNDERWATER SOUND; ACOUSTIC COMMUNICATIONS; ARCTIC REGIONS; AUGMENTATION; BOUNDARY LAYER; CLOUDS; GLACIERS; GRAVITY WAVES; ICE FORMATION; NOISE(SOUND); SCATTERING; STATISTICAL ANALYSIS; SURFACE ROUGHNESS; SURFACE WAVES; WAVE PROPAGATION; Arctic; Sea ice
• Online Access: http://www.dtic.mil/docs/citations/ADA598703; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA598703

The primary long term goals are to measure and model high frequency acoustic propagation and scattering near the sea surface. Processes of particular interest are scattering from surface gravity waves and the effect of whitecaps and bubble clouds on underwater acoustic communications. A secondary long term goal is to exploit measurements of breaking wave noise to infer bubble cloud populations at the sea surface. These original goals have been augmented in 2013 to study ambient noise from glaciers in high latitude regions. Objectives for 2013 The overall program objectives are reproduced below for completeness. Program objectives specific to work in 2013 were to: (1) continue the work of Berry (1972) to deduce the form of surfaces from scattered sound and (2) to measure and analyze the underwater ambient noise marine terminating glaciers in high latitude regions. Berry's research focused on determining the structure of sea ice from scattered sound. He determined some of the basic physical constraints that would limit an inversion method based on reflected pulses interacting with a rough ice surface, but did not present any actual inversions for surface shape. Our objective has been to extend this work to actually determine surface shape from scattered acoustic pulses, and compare the results with experiment. The study of undersea ambient noise in the Arctic is extensive and extends back to the 1960 s, with early results focusing on noise associated with processes in the ice margin. Much of the work on Arctic noise since has been concerned with the generation, propagation and statistical properties of noise generated by sea ice, consistent with the observation that the interaction of the ice cover with the air and water boundary layer is the primary source of noise. More recently, there has been a growing interest in the underwater noise in Arctic fjords, particularly those that contain the terminus of one or more glaciers. The program objective was to mea