Extremely Low Frequency (0.1 to 1.0 mHz) Surf Zone Currents

Abstract Low‐frequency surf zone eddies disperse material between the shoreline and the continental shelf, and velocity fluctuations with frequencies as low as a few mHz have been observed previously on several beaches. Here spectral estimates of surf zone currents are extended to an order of magnit...

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Main Authors: Steve Elgar, Britt Raubenheimer, David B. Clark, Melissa Moulton
Format: Article
Language:English
Published: Wiley 2019-02-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2018GL081106
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author Steve Elgar
Britt Raubenheimer
David B. Clark
Melissa Moulton
author_facet Steve Elgar
Britt Raubenheimer
David B. Clark
Melissa Moulton
author_sort Steve Elgar
collection DOAJ
description Abstract Low‐frequency surf zone eddies disperse material between the shoreline and the continental shelf, and velocity fluctuations with frequencies as low as a few mHz have been observed previously on several beaches. Here spectral estimates of surf zone currents are extended to an order of magnitude lower frequency, resolving an extremely low frequency peak of approximately 0.5 mHz that is observed for a range of beaches and wave conditions. The magnitude of the 0.5‐mHz peak increases with increasing wave energy and with spatial inhomogeneity of bathymetry or currents. The 0.5‐mHz peak may indicate the frequency for which nonlinear energy transfers from higher‐frequency, smaller‐scale motions are balanced by dissipative processes and thus may be the low‐frequency limit of the hypothesized 2‐D cascade of energy from breaking waves to lower frequency motions.
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publishDate 2019-02-01
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record_format Article
series Geophysical Research Letters
spelling doaj-art-cba2fa4ad63f40f4856cb9ff8a2093d42025-08-20T03:49:45ZengWileyGeophysical Research Letters0094-82761944-80072019-02-014631531153610.1029/2018GL081106Extremely Low Frequency (0.1 to 1.0 mHz) Surf Zone CurrentsSteve Elgar0Britt Raubenheimer1David B. Clark2Melissa Moulton3Woods Hole Oceanographic Institution Woods Hole MA USAWoods Hole Oceanographic Institution Woods Hole MA USAClark Geoscience Consulting Santa Cruz CA USAApplied Physics Laboratory University of Washington Seattle WA USAAbstract Low‐frequency surf zone eddies disperse material between the shoreline and the continental shelf, and velocity fluctuations with frequencies as low as a few mHz have been observed previously on several beaches. Here spectral estimates of surf zone currents are extended to an order of magnitude lower frequency, resolving an extremely low frequency peak of approximately 0.5 mHz that is observed for a range of beaches and wave conditions. The magnitude of the 0.5‐mHz peak increases with increasing wave energy and with spatial inhomogeneity of bathymetry or currents. The 0.5‐mHz peak may indicate the frequency for which nonlinear energy transfers from higher‐frequency, smaller‐scale motions are balanced by dissipative processes and thus may be the low‐frequency limit of the hypothesized 2‐D cascade of energy from breaking waves to lower frequency motions.https://doi.org/10.1029/2018GL081106surf zone currentsnearshore processesbreaking wavesvorticity
spellingShingle Steve Elgar
Britt Raubenheimer
David B. Clark
Melissa Moulton
Extremely Low Frequency (0.1 to 1.0 mHz) Surf Zone Currents
Geophysical Research Letters
surf zone currents
nearshore processes
breaking waves
vorticity
title Extremely Low Frequency (0.1 to 1.0 mHz) Surf Zone Currents
title_full Extremely Low Frequency (0.1 to 1.0 mHz) Surf Zone Currents
title_fullStr Extremely Low Frequency (0.1 to 1.0 mHz) Surf Zone Currents
title_full_unstemmed Extremely Low Frequency (0.1 to 1.0 mHz) Surf Zone Currents
title_short Extremely Low Frequency (0.1 to 1.0 mHz) Surf Zone Currents
title_sort extremely low frequency 0 1 to 1 0 mhz surf zone currents
topic surf zone currents
nearshore processes
breaking waves
vorticity
url https://doi.org/10.1029/2018GL081106
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