Temporal characteristics of abyssal finescale motions above rough bathymetry
Toole, John M.
MetadataShow full item record
Current-meter data from a two-year mooring within a fracture zone on the western flank of the Mid-Atlantic Ridge in the South Atlantic Ocean are reported. The mooring, deployed in conjunction with the Brazil Basin Tracer Release Experiment, was placed in the general area where enhanced diapycnal mixing had previously been inferred. The current-meter data characterize the velocity, temperature, shear, and temperature gradient variability as a function of frequency. Energetic velocities and shears were observed at the mooring at a variety of frequencies. In addition to semidiurnal flows, a significant amount of shear variance derived from near-inertial motions, as has been seen in a recent numerical modeling study of tidal-frequency internal wave radiation and wave–wave interaction. At times, a fortnightly modulation of the total superinertial shear variance was indicated in the data, but this signal did not dominate the records. Wave ray tracing indicates that the deeper current meters may have been placed in a shadow zone for locally generated internal tides. At shallower levels, it is suggested that dispersion, wave–wave interaction, and wave breaking effectively obscured the sources of the finescale energy. Average diapycnal diffusivity estimates inferred from a Richardson-number-based parameterization and from observations of temperature inversions at 4648 m were of the same order of magnitude as those derived from turbulent dissipation estimates and from the rate of diapycnal tracer dispersion. The mooring data thus add additional support to the idea that energetic finescale motions above rough bathymetry support enhanced turbulent diapycnal mixing in these regions.
Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 37 (2007): 409–427, doi:10.1175/JPO2988.1.
Showing items related by title, author, creator and subject.
Mooney, T. Aran; Katija, Kakani; Shorter, K. Alex; Hurst, Thomas P.; Fontes, Jorge; Afonso, Pedro (BioMed Central, 2015-09-28)Soft-bodied marine invertebrates comprise a keystone component of ocean ecosystems; however, we know little of their behaviors and physiological responses within their natural habitat. Quantifying ocean conditions and ...
Actin polymerization controls the activation of multidrug efflux at fertilization by translocation and fine-scale positioning of ABCB1 on microvilli Whalen, Kristen E.; Reitzel, Adam M.; Hamdoun, Amro (American Society for Cell Biology, 2012-08-01)Fertilization changes the structure and function of the cell surface. In sea urchins, these changes include polymerization of cortical actin and a coincident, switch-like increase in the activity of the multidrug efflux ...
Paola, Christopher (Woods Hole Oceanographic Institution, 1983-06)The first of two sets of data reported here, measured over two-dimensional immobile current ripples, comprises skin-friction time series at four streamwise positions and velocity profiles measured to within a few mm of ...