Horizontal Lagrangian velocities and accelerations at the surface of steep water-waves are
studied by Particle Tracking Velocimetry for gradually increasing crest heights up to the
inception of a spilling breaker. Localized steep waves are excited using wavemaker-
generated Peregrine breather-type wave trains. Actual crest and phase velocities are
estimated from video recorded sequences of the instantaneous wave shape as well as from
surface elevation measurements by wave gauges. Effects of nonlinearity and spectral width …