Publication:
REFLECTION AND BRAGG SCATTERING ALONG ROCKY SHORES

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Authors
Collins, Patrick
Subjects
rocky shores
Bragg scattering
reflection
directional spectrum
buoy observations
in situ oceanic observations;
Advisors
MacMahan, James H.
Date of Issue
2023-03
Date
Publisher
Monterey, CA; Naval Postgraduate School
Language
Abstract
Field observations of shoreline reflection and Bragg scattering for sea and swell waves along varying rocky shores from Monterey to Santa Cruz, CA, are described in comparison to sandy shores. The estimates are derived from directional spectra obtained primarily from Global Positioning System (GPS)-based Spotter wave-buoys. Wave reflection and Bragg scattering vary by shoreline type, with sandy shores reflecting up to 23% and rocky shores reflecting up to 30% at rocky platforms. However, rocky shores with cliffs reflected up to 14% and rough rocky shores up to 8%. A new estimator is proposed that accounts for the decrease in reflection for rocky shores associated with increasing shoreline roughness and works well for both rocky and sandy shores (r2=0.45). Bragg scattering was expected along rocky shores due to the large bottom roughness and scales that coincide with the resonant response for sea and swell waves. However, the absence of Bragg scattering is believed to be associated with the non-uniformity of the bottom roughness and moderate bottom profile slope, which leads to an insufficient number of wave-bottom interactions for development. The directional narrowing with decreasing water depth is similar to sandy shores. The study describes aspects of sea swell transformation that occurs for rocky shores with observations and theory.
Type
Thesis
Description
Department
Oceanography (OC)
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Distribution Statement
Approved for public release. Distribution is unlimited.
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