LONG-TERM EXAMINATION OF THE INFLUENCES
ON INCIPIENT WAVE BREAKING

T. Mettlach
Neptune Sciences, Inc.
Slidell, LA 70458
K. T. Holland
Naval Research Laboratory
Stennis Space Center, MS 39529-5004
D. May
US Naval Oceanographic Office
Stennis Space Center, MS 39529-5004

Abstract

The Naval Research laboratory's Remote Sensing Applications Branch and Marine Geosciences Division Mapping, Charting and Geodesy Branch have evaluated the accuracy of Navy Surf Model-derived surf zone width estimations. Accurate estimates of surf zone width have became increasingly important for mine countermeasures and amphibious warfare operations. The model is initialized using high quality in situ meteorological, oceanographic and hypsometric data. Model results are compared to surf zone width determined from Argus video imagery acquired at the U.S. Army Corps of Engineers, Field Research Facility, Duck, NC from June 1996 to June 1997 and to results from the Reniers and Battjes (1997) wave transformation model. From 665 video-derived surf zone widths, ranging from 5 to 400 meters, the root-mean-square error in model-derived surf zone width is approximately 30 meters and the mean error is less than 5 meters. The most offshore location where the navy model estimates 10 percent wave breaking is best correlated with the location of incipient wave breaking. However, the correlation of cases with onshore wind and with offshore wind are significantly different, suggesting that wind plays a role in wave breaking processes. Several multiple linear correlation models are developed and used to determine the greatest influences on incipient wave breaking, which are the offshore wave field, the nearshore depth profile and the onshore wind speed. Air-sea temperature differences are shown to be insignificant.

Sponsored by the Office of Naval Research.

Presented to AGU Spring Meeting, 1999.
Abstract