Seismic oceanography: Low-frequency acoustical imaging of oceanic fine-structure.

Abstract

Seismic oceanography, the processing of low-frequency (10–200 Hz) marine reflection data with an emphasis on water-column reflections, has opened up new ways of visualizing thermohaline finestructure. Studies to date have produced stunning images of fronts, eddies, water mass boundaries, and internal waves. As it approaches its sixth birthday as a discipline, seismic oceanography is entering a critical stage of development. An early rush to document the physical basis for the reflections and to catalog images in different oceanic environments is yielding to an effort to extract useful, trustable, and quantitative information on physical oceanographic processes from the images. Here we review progress to date and point to key areas of current and future works. Promising areas of research include emerging techniques to quantify internal wave energy and turbulence dissipation from seismic images, the acquisition of industry SO data, and the production of three-dimensional and time-lapse images of finestructure. A principal challenge for the future is the merging of synthetic and field seismic data with realistic physical models of oceanic temperature/density structure, calculated at the dense horizontal and vertical spacings needed to simulate the seismic data.