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Observations of runup and energy flux on a low‐slope beach with high‐energy, long‐period ocean swell
Author(s) -
Fiedler Julia W.,
Brodie Katherine L.,
McNinch Jesse E.,
Guza Robert T.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl066124
Subject(s) - infragravity wave , geology , swell , wave height , energy flux , surf zone , wind wave , wavelength , shore , swash , submarine pipeline , energy balance , geomorphology , oceanography , physics , wave propagation , mechanical wave , astronomy , longitudinal wave , optoelectronics , quantum mechanics , thermodynamics
The transformation of surface gravity waves from 11 m depth to runup was observed on the low‐sloped (1/80) Agate Beach, Oregon, with a cross‐shore transect of current meters, pressure sensors, and a scanning lidar. Offshore wave heights H 0 ranged from calm (0.5 m) to energetic (>7 m). Runup, measured with pressure sensors and a scanning lidar, increases linearly with ( H 0 L 0 ) 1/2 , with L 0 the deep‐water wavelength of the spectral peak. Runup saturation, in which runup oscillations plateau despite further increases in ( H 0 L 0 ) 1/2 , is not observed. Infragravity wave shoaling and nonlinear energy exchanges with short waves are included in an infragravity wave energy balance. This balance closes for high‐infragravity frequencies (0.025–0.04 Hz) but not lower frequencies (0.003–0.025 Hz), possibly owing to unmodeled infragravity energy losses of wave breaking and/or bottom friction. Dissipative processes limit, but do not entirely damp, increases in runup excursions in response to increased incident wave forcing.