Structure and Dynamics of the Benthic Boundary Layer above the Hatteras Abyssal Plain.
Abstract
The structure of the near-bottom velocity and density fields was observed for 3 months with a fixed velocity/temperature measuring array on the Hatteras Abyssal Plain. The velocity signal was examined for structure coherent with the observed mixed layers. Velocity fluctuations above 1 cph increase in energy near the bottom, especially within bottom mixed layers. The frequency and energy of these fluctuations is consistent with the expected properties of boundary layer turbulence. The turbulence as measured by these velocity fluctuations, is modulated on tidal and inertial time scales and extends intermittently throughout the bottom mixed layer. The clockwise near inertial velocity fluctuations, presumably due to internal waves, also show structure coherent with the observed mixed layers. Their energy decreases near the top of the mixed layer with little phase change. Within the mixed layer the phase begins to lead, with the phase increasing downward. The near inertial anticlockwise velocity fluctuations show far less coherence with the mixed layer structure; higher frequency internal wave band velocity fluctuations show very little coherence with the mixed layer structure. The characteristic boundary layer velocity signal in both the high frequency and near inertial bands commonly extends throughout the mixed layer, often significantly above the estimated turbulent Ekman layer height. These observations are inconsistent with a steady turbulent Ekman layer model of the boundary layer. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1981
- Accession Number
- ADA099137
Entities
People
- Eric A. D'Asaro
Organizations
- Woods Hole Oceanographic Institution