HR: 14:00h
AN: OS13C-02 INVITED     [Abstracts]
TI: Detailed Characterization of Nearshore Processes During NCEX
AU: * Holland, K
EM: tholland@nrlssc.navy.mil
AF: Naval Research Laboratory, Code 7440.3, Stennis Space Center, MS 39529 United States
AU: Kaihatu, J M
EM: kaihatu@nrlssc.navy.mil
AF: Naval Research Laboratory, Code 7322, Stennis Space Center, MS 39529
AU: Plant, N
EM: nplant@nrlssc.navy.mil
AF: Naval Research Laboratory, Code 7440.3, Stennis Space Center, MS 39529 United States
AB: Recent technology advances have allowed the coupling of remote sensing methods with advanced wave and circulation models to yield detailed characterizations of nearshore processes. This methodology was demonstrated as part of the Nearshore Canyon EXperiment (NCEX) in La Jolla, CA during Fall 2003. An array of high-resolution, color digital cameras was installed to monitor an alongshore distance of nearly 2 km out to depths of 25 m. This digital imagery was analyzed over the three-month period through an automated process to produce hourly estimates of wave period, wave direction, breaker height, shoreline position, sandbar location, and bathymetry at numerous locations during daylight hours. Interesting wave propagation patterns in the vicinity of the canyons were observed. In addition, directional wave spectra and swash / surf flow velocities were estimated using more computationally intensive methods. These measurements were used to provide forcing and boundary conditions for the Delft3D wave and circulation model, giving additional estimates of nearshore processes such as dissipation and rip currents. An optimal approach for coupling these remotely sensed observations to the numerical model was selected to yield accurate, but also timely characterizations. This involved assimilation of directional spectral estimates near the offshore boundary to mimic forcing conditions achieved under traditional approaches involving nested domains. Measurements of breaker heights and flow speeds were also used to adaptively tune model parameters to provide enhanced accuracy. Comparisons of model predictions and video observations show significant correlation. As compared to nesting within larger-scale and coarser resolution models, the advantages of providing boundary conditions data using remote sensing is much improved resolution and fidelity. For example, rip current development was both modeled and observed. These results indicate that this approach to data-model coupling is tenable and may be useful in near-real-time characterizations required by many applied scenarios.
DE: 4512 Currents
DE: 4546 Nearshore processes
DE: 4560 Surface waves and tides (1255)
DE: 3020 Littoral processes
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting