HR: 14:35h
AN: OS13C-04    [Abstracts]
TI: Offshore Directed Flows in the Surf Zone From Video
AU: * Clarke, L
EM: lclarke@coas.oregonstate.edu
AF: College of Oceanic and Atmospheric Sciences, Oregon State University, 104 COAS Admin Bldg, Corvallis, OR 97331 United States
AU: Holman, R
EM: holman@coas.oregonstate.edu
AF: College of Oceanic and Atmospheric Sciences, Oregon State University, 104 COAS Admin Bldg, Corvallis, OR 97331 United States
AB: Pixel intensity time series from surf zone video imagery are used to explore identification of rip currents and characterization of temporal variability in rip velocity based on localized reduction in shallow water wave celerity owing to interaction between incident gravity waves and offshore-directed currents. Time-varying occurrence and velocity of offshore-directed surf zone flows such as rip currents interact with incoming waves and bores reducing wave celerity from theoretical shallow water speed. Wave celerity is estimated using cross-spectral analysis of 17 minute pixel intensity time series sampled across the surf zone at Blacks Beach, California. Variation in estimated celerity over several hours is compared with expected variation in celerity given measured bathymetry and change in water level. Deviation from expected change in celerity is mapped across the surf zone with the aim of identifying regions of significant rip current flow. Estimation of wave celerity and variation over shorter time scales (1-2min) is explored in an attempt to identify short period fluctuations in rip current velocity.
DE: 4546 Nearshore processes
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting