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Detailed Reference Information |
MacMahan, J.H., Reniers, A.J.H.M., Thornton, E.B. and Stanton, T.P. (2004). Surf zone eddies coupled with rip current morphology. Journal of Geophysical Research 109: doi: 10.1029/2003JC002083. issn: 0148-0227. |
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Energetic very low frequency (VLF; frequencies <0.004 Hz) surf zone eddies (SZEs) were observed on a beach composed of shore-connected shoals with quasi-periodic (~125 m) incised rip channels at Sand City, Monterey Bay, California. Incident waves consisted of predominantly shore-normal narrow-banded swell waves. SZEs were located outside the gravity region in alongshore wave number, ky, spaced within the VLF band, and did not appear to exist in higher-frequency bands. The SZEs were significant (Urms,VLF ~ 0.25 m/s) and constant in intensity within the surf zone (shore-connected shoals and rip channels) and rapidly decreased offshore. The alongshore and cross-shore SZE velocity variances were similar in magnitude. VLF SZE velocities were not forced by VLF surface elevations and were not well correlated with rip current flows (r2 = 0.18). There is an indication that the SZEs were related to wave forcing, with the SZEs statistically correlated with incoming sea-swell wave height (r2 = 0.49). F-ky spectral estimates illustrate a strong relationship between rip channel spacing and SZE cross-shore velocities (ky = ¿0.008 m-1) and minimal SZE alongshore velocity variation (ky = 0 m-1). Data analysis suggests that the SZEs are not simply instabilities of an unstable rip current jet. A simple conceptual model suggests that SZE f-ky spectra can be explained by the entire rip current circulation cells oscillating predominantly in the cross shore and slightly in the alongshore. |
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BACKGROUND DATA FILES |
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Abstract |
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Keywords
Oceanography, Physical, Nearshore processes, Marine Geology and Geophysics, Littoral processes, Oceanography, Physical, Currents, Oceanography, Physical, General or miscellaneous, rip currents, surf zone, nearshore, eddies, circulation, waves |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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