van Haren, H., A. A. Cimatoribus, F. Cyr, and L. Gostiaux
Geophys. Res. Lett., 43 2016GL068032.16 (2016)
A unique small-scale 3-D mooring array has been designed consisting of five parallel lines, 100 m long and 4 m apart, and holding up to 550 high-resolution temperature sensors. It is built for quantitative studies on the evolution of stratified turbulence by internal wave breaking in geophysical flows at scales which go beyond that of a laboratory.
Here we present measurements from above a steep slope of Mount Josephine, NE Atlantic where internal wave breaking occurs regularly. Vertical and horizontal coherence spectra show an aspect ratio of 0.25–0.5 near the buoyancy frequency, evidencing anisotropy. At higher frequencies, the transition to isotropy (aspect ratio of 1) is found within the inertial subrange. Above the continuous turbulence spectrum in this subrange, isolated peaks are visible that locally increase the spectral width, in contrast with open ocean spectra. Their energy levels are found to be proportional to the tidal energy level.