In the early 1960’s, the physical oceanography community was rudely awakened from their pursuit of “Direct Current” (D.C.) oceanography. John Swallow had acoustically tracked deep floats; instead of drifting in parallel at a few mm per second, as predicted by circulation models, the floats moved in different directions at 10 cm/s. There followed a series of ambitious experiments: the Soviet POLYGON moorings, the Mid-Ocean Dynamics Experiment (MODE) and POLYMODE. By the mid-1970’s it had become clear that most of the pelagic kinetic energy is associated not with the steady circulation but with eddies of 100 km and 100 day scales.

Munk, W.H., and P.F. Worcester. 1988. Ocean acoustic tomography. Oceanography 1(1):8–10, https://doi.org/10.5670/oceanog.1988.31.

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