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Lowfrequency, manyminuteperiod horizontal surfzone eddies are an important mechanism for the dispersion of material, transporting larvae, pollutants, sediment, and swimmers both across and along the nearshore. Previous numerical, laboratory, and field observations on alongshore uniform bathymetry with no or roughly uniform mean background flows suggest that the lowfrequency eddies may be the result of a twodimensional inverse energy cascade that transfers energy from relatively small spatialscale vorticity injected by depth limited breaking waves to larger and larger spatial scales. Here, using remotely sensed highspatial resolution estimates of currents, those results are extended to surfzones with strong complex mean circulation patterns [flows O(1 m/s)] owing to nonuniform bathymetry. Similar to previous results, wavenumber spectra and secondorder structure functions calculated from the observations are consistent with a twodimensional inverse energy cascade. The size of the largest eddies is shown to depend on the surfzone width and the spatial scales of the mean currents. Thirdorder structure functions also are consistent with an inverse cascade for spatial scales greater than ∼50 m. At smaller scales, the thirdorder structure functions suggest a mixture of inverse and forward cascades.
more » « less Award ID(s):
 1948137
 NSFPAR ID:
 10489205
 Publisher / Repository:
 AIP
 Date Published:
 Journal Name:
 Physics of Fluids
 Volume:
 35
 Issue:
 8
 ISSN:
 10706631
 Format(s):
 Medium: X
 Sponsoring Org:
 National Science Foundation
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