Wave Breaking Eddies And Transient Rip Current Dynamics In Large-Scale Wave Basin Experiments


  • CHRISTINE M. BAKER Civil and Environmental Engineering, Stanford University, U.S.A.
  • MELISSA MOULTON Applied Physics Laboratory, University of Washington, U.S.A.
  • C. CHRIS CHICKADEL Applied Physics Laboratory, University of Washington, U.S.A
  • EMMA S. NUSS Civil and Environmental Engineering, University of Washington, U.S.A.
  • MARGARET PALMSTEN Coastal and Marine Science Center, U.S. Geological Survey, U.S.A.
  • KATHERINE BRODIE U.S. Army Corps of Engineers Research and Development Center, U.S.A.




directional wave basin, short-crested wave breaking, surfzone eddies, rip currents, remote sensing


Rip currents transport contaminants, nutrients, larvae, and, unfortunately, occasionally even swimmers between the surf zone and inner shelf. Transient rip currents are ephemeral ejections associated with surfzone eddies that are ubiquitous even on alongshore-uniform beaches. During directionally spread wave conditions, depth-limited breaking along finite-length regions, known as short-crested breaking, leads to spatial variation in the breaking force and corresponding vertical vorticity input to the water column. An inverse energy cascade from the injected vorticity may result in larger scale horizontal surfzone eddies, consistent with two-dimensional turbulence. These large-scale eddies enhance dispersion within the surf zone and may mutually advect offshore as a transient rip current. While this hypothesis is widely discussed in the literature, we do not have strong observational evidence for the processes connecting the wave field to the formation of large-scale horizontal eddies. To overcome the challenges of isolating and measuring the processes leading to transient rip currents in the field, we examined these processes in large-scale laboratory experiments.




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