|Title||Observations of runup and energy flux on a low-slope beach with high-energy, long-period ocean swell|
|Publication Type||Journal Article|
|Year of Publication||2015|
|Authors||Fiedler J.W, Brodie K.L, McNinch J.E, Guza RT|
|Journal||Geophysical Research Letters|
|Type of Article||Article|
|Keywords||climate; dissipation; infragravity waves; intermediate; motions; nearshore; setup; Surfzone; swash oscillations; variability|
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 (H0L0)(1/2), with L-0 the deep-water wavelength of the spectral peak. Runup saturation, in which runup oscillations plateau despite further increases in (H0L0)(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.