Sound scattering from oceanic turbulence

[1] The first near coincident measurements of acoustic backscatter and temperature/velocity microstructure confirm theoretical predictions that oceanic turbulence scatters sound. Not only are acoustic backscatter at 307 kHz and turbulent microstructure unambiguously correlated on a patch-by-patch basis, but measured scattering amplitudes agree with theoretical predictions for scattering from turbulent microstructure. Nearby plankton net-hauls indicate that there were far too few zooplankton in the turbulent regions to account for the scattering intensity. At an acoustic frequency of 307 kHz, backscatter from salinity microstructure can be as strong as or stronger than the signal from a zooplankton scattering layer. There are two important consequences of these strong scattering results. First, they suggest the feasibility of using acoustics to remotely sense oceanic turbulence. Second, they could easily confound acoustic zooplankton biomass estimates in turbulent regions.