The influence of bubble clouds on surface scattering strengths

One of the most comprehensive sets of surface scattering strength measurements was made during the CST experiments between August 1988 and May 1993, covering a frequency range from ∼70 to ∼1500 Hz. An extensive set of environmental measurements (including bubble cloud measurements) collected on several of these experiments make this a unique data set for examining the effect of sub-surface bubble clouds on surface backscattering strength. Analysis of these data have shown that wind speed, while the most important environmental descriptor, cannot by itself explain some important differences in the surface scattering strengths measured for the different CST experiments. These differences appear to be linked to the sub-surface bubble clouds which, in turn, are influenced by the dynamics of the upper layers of the ocean. Latest results from the continuing analysis of the surface scattering and bubble cloud data will be presented which illustrate the influence of the bubble clouds and indicate how the stability of the upper layers of the ocean play a role in distributing those bubble clouds. [Work supported by ONR.]