Forcing and variability of nonstationary rip currents

Journal of Geophysical Research C: Oceans
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Abstract

Surface wave transformation and the resulting nearshore circulation along a section of coast with strong alongshore bathymetric gradients outside the surf zone are modeled for a consecutive 4 week time period. The modeled hydrodynamics are compared to in situ measurements of waves and currents collected during the Nearshore Canyon Experiment and indicate that for the entire range of observed conditions, the model performance is similar to other studies along this stretch of coast. Strong alongshore wave height gradients generate rip currents that are observed by remote sensing data and predicted qualitatively well by the numerical model. Previous studies at this site have used idealized scenarios to link the rip current locations to undulations in the offshore bathymetry but do not explain the dichotomy between permanent offshore bathymetric features and intermittent rip current development. Model results from the month‐long simulation are used to track the formation and location of rip currents using hourly statistics, and results show that the direction of the incoming wave energy strongly controls whether rip currents form. In particular, most of the offshore wave spectra were bimodal and we find that the ratio of energy contained in each mode dictates rip current development, and the alongshore rip current position is controlled by the incident wave period. Additionally, model simulations performed with and without updating the nearshore morphology yield no significant change in the accuracy of the predicted surf zone hydrodyanmics indicating that the large‐scale offshore features (e.g., submarine canyon) predominately control the nearshore wave‐circulation system.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Forcing and variability of nonstationary rip currents
Series title Journal of Geophysical Research C: Oceans
DOI 10.1002/2015JC010990
Volume 121
Issue 1
Year Published 2016
Language English
Publisher American Geophysical Union
Contributing office(s) St. Petersburg Coastal and Marine Science Center
Description 20 p.
First page 520
Last page 539
Time Range Start 2003-10-01
Online Only (Y/N) N
Additional Online Files (Y/N) N