Oceanography Seminar - Assaf Azouri

November 1, 3:00pm - 4:15pm
Mānoa Campus, Marine Science Building 114

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“Observations and Modeling of Coastal Infragravity Waves”

Many coastal regions are exposed to energetic short-period gravity waves. As they approach the shore, they lose much of their energy during the breaking process. Although frictional processes dissipate some of that energy, most of it is transferred to longer waves, commonly known as infragravity (IG) waves. IG waves often dominate the sea level and current variability in the surf zone, and they strongly influence coastal processes such as sediment transport, rip currents, sand bar formation, harbor and coastal resonances (seiches), and ultimately wave runup. This presentation will show observations of IG waves on O’ahu’s North Shore, a coastline that is exposed to highly energetic sea/swell forcing throughout most of the year. The results reveal that the response of the coastline, including a small boat harbor, is dominated by a suite of modes ranging in periods from 1 minute to nearly 30 minutes.

These observational findings are combined with numerical modeling, in order to help us reconstruct the spatial distribution of the IG wave field for swell conditions where no data is available. As a first step, three high-resolution, dispersive nearshore numerical models (BOSZ - Roeber & Cheung, 2012; FUNWAVE - Shi et al., 2012; XBeach - Roelvink et al., 2009) are compared and contrasted with our harbor and reef observations, in an attempt to test their ability to reproduce the wave transformation processes in the complex Hawaiian reef-system environment. Results generated with outputs from all three models are in good agreement with the observations. Overall, the models replicate the spectral amplitudes and capture most of the observed auto- and cross-spectral details.

Further analysis using one of the models reveals complex spatial IG wave patterns. In particular, our simulations highlight standing IG waves modified by the coastal morphology, with alongshore symmetry that varies with frequency. The existence of such standing wave structures may result in strong currents across the sea level nodal lines. These wave forms are not unique to the North Shore of O’ahu as they can be found at other coastlines.

Event Sponsor
Oceanography Department , Mānoa Campus

More Information
Phil Thompson, (808) 956-6574, philiprt@hawaii.edu, http://www.soest.hawaii.edu/oceanography/seminar.html, 11-1-18 Assaf Azouri (PDF)

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Thursday, November 1
9:30am	Architecture Final Oral Mānoa Campus, ARCH 214
10:00am	Go Out & Vote Mānoa Campus, Campus Center
10:30am	Health & Wellness Ê»Ohana Resource Fair Mānoa Campus, UHM Campus Center Courtyard
12:00pm	Geography & Environment Seminar Series Mānoa Campus, 443 Saunders
12:00pm	"Wounded Narratives: Jewish Childhood Recollections in Post-Soviet Autobiogra Mānoa Campus, Kuykendall 409A
12:00pm	“Wounded Narratives: Jewish Childhood Recollections” Mānoa Campus, The Center for Biographical Research
2:30pm	Architecture Final Oral Mānoa Campus, ARCH 314
3:00pm	“Give the Palestinian People the Right to Tell Their Own Stories” Mānoa Campus, KUY 410
3:00pm	Forum : Film, Fact, Fiction, and Fear Mānoa Campus, Art Building, Rm. 101 (lecture hall)
3:00pm	Oceanography Seminar - Assaf Azouri Mānoa Campus, Marine Science Building 114
5:00pm	Shadowing and Networking Workshop Mānoa Campus, Webster Hall, Room 203
6:30pm	Sakamaki Extraordinary Lecture: Myths & Misconceptions about Creativity Mānoa Campus, Archtecture Auditorium
6:30pm	Hanauma Bay Educational Lecture Series Hanauma Bay Nature Preserve Theater
7:00pm	Diálogos virtuales / Virtual dialogues: Work the Pacific Mānoa Campus, Art Building, Photo Lab