Acoustic Warfare: Bubble Clouds
MITRE CORP MCLEAN VA JASON PROGRAM OFFICE
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In this report, we survey the basic ingredients that go into the bubble cloud hypothesis for the enhanced acoustic backscatter seen at high enough frequency and wind speed. The basic picture that has been proposed is that spilling waves generate foamy water which is then subducted downward, modifying the local sound velocity. One proposed mechanism for the downwelling current necessary to accomplish the required subduction is the Langmuir circulation cell we will see that this is sufficient but other mechanisms may also contribute. Our discussion naturally breaks up into the hydrodynamics issues related to bubble generation and subduction and to acoustic issues related to scattering from a given distribution of air density below the surface. acoustic backscatter, bubble clouds, Laplace Green, langmuir, circulations.