Internal tides and boundary mixing imaged on the Norwegian continental slope

HR: 0800h
AN: OS21C-1250 [Abstracts]
TI: Internal tides and boundary mixing imaged on the Norwegian continental slope
AU: * Holbrook, W S
EM: steveh@uwyo.edu
AF: University of Wyoming, Dept. of Geology and Geophysics #3006, laramie, WY 82072-3006 United States
AU: Fer, I
EM: ilker.fer@gfi.uib.no
AF: Bjerknes Centre for Climate Research, Geofysisk institutt AllＨaten 70, Bergen, N-5007 Norway
AU: Nandi, P
EM: pnandi@uwyo.edu
AF: University of Wyoming, Dept. of Geology and Geophysics #3006, laramie, WY 82072-3006 United States
AU: Paramo, P
EM: paramo@uwyo.edu
AF: University of Wyoming, Dept. of Geology and Geophysics #3006, laramie, WY 82072-3006 United States
AB: Boundary mixing on continental slopes and other topographic features may help maintain the ocean's stratification by converting low-mode internal wave energy into increased potential energy via turbulence, but existing observations are too sparse to assess whether this process is sufficiently widespread to affect global balances. Here we present a new method for identifying and quantifying internal wave processes in the ocean by acoustic imaging. Seismic reflection images of thermohaline finestructure in the Norwegian Sea that show semidiurnal (M2) internal waves and associated zones of turbulent disruption of finestructure on the continental slope of Norway. The disrupted zone occur at water depths of ~500-650 m, where the slope is critical to M2 internal waves and the water column is highly stratified. Wavenumber spectra calculated from finestructure displacements in the disrupted zones show enhanced energy levels, relative to both open-ocean finestructure and the Garrett-Munk spectrum. These results imply that seismic reflection profiling can remotely detect internal waves, identify the locations and dimensions of sites of boundary mixing, and provide quantitative estimates of internal wave energy in the ocean.
DE: 4544 Internal and inertial waves
DE: 4594 Instruments and techniques
DE: 0910 Data processing
DE: 0930 Oceanic structures
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting