HR: 17:15h
AN: OS24A-06    [Abstracts]
TI: Characterization of Wave-Induced Boundary Layers Over a Rough Bottom
AU: * Bandet, M D
EM: marionb@hawaii.edu
AF: Department of Ocean and Resources Engineering, University of Hawaii, 2540 Dole Street, Holmes Hall 402 , Honolulu, HI 96822 United States
AU: Pawlak, G
EM: pawlak@hawaii.edu
AF: Department of Ocean and Resources Engineering, University of Hawaii, 2540 Dole Street, Holmes Hall 402 , Honolulu, HI 96822 United States
AU: Stanton, T P
EM: stanton@nps.edu
AF: Department of Oceanography, Naval Postgraduate School, Graduate School of Engineering, Monterey, CA 93943 United States
AB: Field observations of the wave-induced flow over a fixed coral rough boundary were carried out in summer 2004 on the south shore of Oahu, Hawaii. Turbulent motions along the seabed generated by the oscillatory motion of surface waves are of great interest in coastal waters because wave boundary layers are the site of sediment entrainment, suspension and transport from the seabed as well as wave energy dissipation. The nature of this turbulent boundary layer over very rough bathymetry such as that characteristic of coral reef is not well-understood, although this type of inhomogeneous roughness is pervasive in natural settings. The observations were the first measurements carried out within a nearshore observatory presently under development that allows real-time characterization of the dynamic, tide and wave influenced reef environment. A downward-looking Bistatic Current Doppler Velocimeter (BCDV), mounted on an automated horizontal profiler, was used to obtain a 1cm vertical resolution, two-dimensional view of the wave-boundary layer over a wave orbital excursion ($\sim$2m). The bed morphology along the profile track was mapped using a scanning laser altimetry system. The objective of these measurements is to resolve the 2-D spatial structure of the oscillating boundary layer in a phase-averaged sense and to calculate spatial averages of Reynolds stresses and turbulent dissipation. The horizontal profiler allows integration of these quantities over the high spatial variability expected over very rough boundaries. Preliminary analysis of the field data set is presented here.
DE: 4524 Fine structure and microstructure
DE: 4546 Nearshore processes
DE: 4594 Instruments and techniques
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting