Radiation Stress Spectral Transformation Across the Surf Zone

摘要

Shoaling and decay of bi-modal spectra (two distinct frequency peaks anddirections) were measured at Santa Barbara Beach, California. Spectral analysis shows that the wave train associated with the lower frequency peak dominates in the surf zone with the high frequency component decaying faster than low frequency component. Mean wave directions were measured for both wave trains with current meters located outside and throughout the surf zone. Errors associated with meter is-alignment were minimized by numerically rotating the measured mean wave direction of the low frequency wave component to correspond with the predicted refracted direction based on Snell's Law over the near planar beach. Meter re-alignments were then verified by comparing the measured and predicted directions of the high frequency component, yielding an average error of order one degree. The ability to remove rotational errors from in-situ data thereby allows for accurate measurements of the radiation stress transformation across the surf zone. Nearshore Wave Processes, Longshore Currents.