Tidal modulation of infragravity waves via nonlinear energy losses in the surfzone
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Authors
Thomson, James M.
Elgar, Steve
Raubenheimer, Britt
Herbers, T.H.C.
Guza, R.T.
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Advisors
Date of Issue
2006-03-01
Date
Publisher
American Geophysical Union
Language
en_US
Abstract
The strong tidal modulation of infragravity (200 to 20 s period) waves observed
on the southern California shelf is shown to be the result of nonlinear
transfers of energy from these low-frequency long waves to higher-frequency
motions. The energy loss occurs in the surfzone, and is stronger as waves propagate
over the convex low-tide beach profile than over the concave high-tide
profile, resulting in a tidal modulation of seaward-radiated infragravity energy.
Although previous studies have attributed infragravity energy losses
in the surfzone to bottom drag and turbulence, theoretical estimates using
both observations and numerical simulations suggest nonlinear transfers dominate.
The observed beach profiles and energy transfers are similar along several
km of the southern California coast, providing a mechanism for the tidal
modulation of infragravity waves observed in bottom-pressure and seismic
records on the continental shelf and in the deep ocean.
Type
Article
Description
The article of record as published may be found at https://doi.org/10.1029/2005GL025514
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Support was provided
by ONR and NSF.
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Citation
Geophysical Research Letters 33 (2006): L05601, doi:10.1029/2005GL025514.
Geophysical Research Letters 33 (2006): L05601
Geophysical Research Letters 33 (2006): L05601