Internal Waves and Turbulence in the Deep Ocean

Abstract

Energy densities as a function of frequency of the vertical and relative horizontal velocities of water in the deep ocean as measured at clusters of neutrally buoyant floats are compared for different locations in the North Atlantic Ocean. The comparisons cover a range of frequencies f from somewhat above inertial to values higher than the Väisälä frequency fv. The spectra for velocities of float separation fell with frequency at a rate of approximately f?3. Vertical velocity spectra determined for the water fell as f?5 to f?7 at frequencies >0.6 fv. Coherences were generally poor and often had values associated with randomness. The coherences between vertical motions and the temperatures present at a float were smaller than might he expected. Despite the small coherences it is argued that most of the kinetic energy is associated with non-mixing or internal wave type motions.