HR: 0800h
AN: OS11A-0490    [Abstracts]
TI: Remote Sensing of Radiation Stress Gradients from NCEX Optical Imagery
AU: * Killian, J R
EM: jkillian@coas.oregonstate.edu
AF: College of Oceanic and Atmospheric Sciences, Oregon State University, 104 COAS Administration Building, Corvallis, OR 97331
AU: Holman, R A
EM: holman@coas.oregonstate.edu
AF: College of Oceanic and Atmospheric Sciences, Oregon State University, 104 COAS Administration Building, Corvallis, OR 97331
AB: As waves break in the surf zone, radiation stress gradients are created, corresponding to a local net addition of momentum to the water column and resulting in a driving force for nearshore currents and subsequent sediment transport. Consequently, estimation of radiation stress gradients throughout a given domain is of great interest for both the initilization and analysis of nearhore circulation model results. Currently, such estimates are based on first-order differences in cross-shore momentum flux calculated from {\it in situ} data recorded at discrete locations. We are investigating the potential for optical signals of wave breaking to provide an alternate remote sensing technique for the direct estimation of radiation stress gradient fields. For a beach with straight, parallel contours, the individual components of radiation stress gradients can be derived from linear wave theory and depend on local celerity, wave angle, and rate of dissipation, all of which have optical signatures. Our current work focuses on extending these equations to include spectral wave information over more complex bathymetry. In addition, the inclusion of a more sophisticated breaker intensity model allows for more accurate and robust estimation of dissipation. Initial results for the cross-shore gradient in longshore directed momentum compare well with numerical model results during the NCEX field experiment.
DE: 4275 Remote sensing and electromagnetic processes (0689)
DE: 4546 Nearshore processes
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting