Sound speed requirements for optimal imaging of seismic oceanography data

Low‐frequency acoustic imaging of internal oceanic structure (“seismic oceanography”) is providing unprecedented views of thermohaline finestructure with the potential to provide quantitative information on such processes as internal waves, eddy dynamics, and turbulent dissipation. Producing seismic images clear enough to confidently extract such information requires accurate sound‐speed models. Because sound‐speed modeling is time‐intensive, and oceanic sound speed relatively simple compared to the solid earth, simplistic assumptions of ocean sound speeds have some appeal in seismic processing of ocean reflections. Here, we consider the effect on seismic images of four sound‐speed models: (1) a uniform sound speed of 1500 m/s, (2) regional data from an archived database, (3) temperature profiles collected concurrently with the seismic data, and (4) standard user‐selected profiles. Our results show the inadequacy of simple “shortcut” models (1 and 2) and indicate the necessity of rigorous, locally derived sound‐speed models (3 and 4).