### Abstract:

The wave-induced velocity field in the nearshore is composed of contributions from incident wind waves (f
> 0.05 Hz), surface infragravity waves (f < 0.05 Hz, lkl < (σ²/gβ) and shear waves (f < 0.05 Hz, lkl > σ²/gβ),
where ƒ is the frequency, σ = 2πf, k is the radial alongshore wavenumber (2π/L, L being the alongshore wavelength),
β is the beach slope, and g is the acceleration due to gravity. Using an alongshore array of current
meters located in the trough of a nearshore bar (mean depth ≈ 1.5 m), we investigate the bulk statistical behaviors
of these wave bands over a wide range of incident wave conditions. The behavior of each contributing
wave type is parameterized in terms of commonly measured or easily predicted variables describing the beach
profile, wind waves, and current field. Over the 10-day period, the mean contributions (to the total variance) of
the incident, infragravity, and shear wave bands were 71.5%, 14.3% and 13.6% for the alongshore component
of flow (mean rms oscillations of 44,20, and 19 cm s¯¹, respectively), and 81.9%, 10.9%, and 6.6% for the
cross-shore component (mean rrns oscillations of 92, 32, and 25 cm s¯¹, respectively). However, the values
varied considerably. The contribution to the alongshore (cross-shore) component of flow ranged from 44.8-
88.4% (58.5-95.8%) for the incident band, to 6.2-26.6% (2.5-32.4%) for the infragravity band, and 3.4-
33.1 % (0.6-14.3%) for the shear wave band. Incident wave oscillations were limited by depth-dependent saturation
over the adjacent bar crest and varied only with the tide. The infragravity wave rms oscillations on this
barred beach are best parameterized by the offshore wave height, consistent with previous studies on planar
beaches. Comparison with data from four other beaches of widely differing geometries shows the shoreline
infragravity amplitude to be a near-constant ratio of the offshore wave height. The magnitude of the ratio is
found to be dependent on the Iribarren number, ξ₀ = β(H/L₀)¯1/2. Shear waves are, as previous observation and
theory suggest (Oltman-Shay et al., 1989; Bowen and Holman, 1989), significantly correlated with a
prediction of the seaward facing shear of the longshore current.