Comments from ONR's Ocean Acoustics Program
Jeffrey Simmen
Office of Naval Research, Code 321
Arlington, Virginia 22217
Ocean Acoustics Program
The Ocean Acoustics Program of the Office of Naval Research (ONR) is a theoretical and experimental research program which addresses the physics of the generation, propagation, and scattering of acoustic (and elastic) waves in the (spatially and temporally varying) ocean environment. The program primarily emphasizes theforward problem of predicting the characteristics of the sound field given knowledge of the ocean environment, but it also secondarily addresses the inverse problem of using the details of the sound field to deduce the morphology and dynamics of the ocean environment. ‘Ocean environment’means not only the ocean volume but also the air-ocean interface and the ocean bottom/subbottom; therefore, this program addresses the interaction of sound with a variety of environmental features, including ocean mesoscale, internal waves, turbulence, surface waves, bubbles, zooplankton, fish, seafloor roughness, and ocean subbottom inhomogeneities. By necessity this program has a strong connection with other ocean environmental programs, in particular, those programs concerned with physical oceanography, marine geology & geophysics, and ocean biology. It should be noted that ONR is essentially the only U.S. government agency that funds basic researchin ocean acoustrcs.
Program Directions
ONR's Ocean Acoustics Program has several new programmatic goals. One goal is that for all major ocean acoustics field experiments, detailed environmental measurements be made simultaneous with complete acoustics measurements, to allow more complete and accurate description of the cause and effect between environmental behavior and acoustical phenomena (e.g., fluctuations). There are several recent examples (e.g., SWARM and Shelfbreak PRIMER) of ONR-funded acoustics experiments having comprehensive oceanographic measurements at the same time as the acoustics measurements. This approach to experiments, requiring more complete environmental characterization, substantially increases the costs of field efforts. Therefore, a second goal, particularly relevant to field efforts, is that the Ocean Acoustics Program pool resources, between U.S. programs and between countries. This pushto increase international collaboration and cooperation in ocean acoustics has already resulted in joint efforts, in shallow-water acoustics with the Chinese and in long-range propagation with the Russians, as examples. Another program goal is to increase connectivity by use of the Internet. Information about the Ocean Acoustics Program, including program content, direction, anddeadlines, can now be found on the ONR homepage (www.onr.navy.mil); acoustic modeling software and data can be found in the ONR-sponsored Ocean Acoustics Library (oalib.njit.edu).
