High-frequency broadband (150–600 kHz) acoustic backscattering from oceanic microstructure and zooplankton in the presence of internal solitary waves

Abstract

As one of the founders of acoustical oceanography, Hank Medwin has directly or indirectly influenced the careers of many scientists. Throughout his illustrious and prolific career, Hank Medwin was passionate about using and developing acoustic techniques to study the ocean and, in particular, to study the physical processes of the ocean interior, a passion shared by the authors. In this spirit, the authors present highlights of an experiment in which a high-frequency broadband (150–600 kHz) acoustic backscattering system was used to investigate the scattering of sound from oceanic microstructure and zooplankton throughout the evolution, from generation to dissipation, of internal solitary waves. The broadband spectrum of the scattered returns is used to differentiate between regions in which the scattering is dominated by zooplankton versus microstructure. Interpretation of the measured scattering relies heavily on a fundamental understanding of scattering processes as well as on direct measurements of microstructure and biology.