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Author MacMahan, James Howard
Title Field observations of rip currents
book jacket
Descript 224 p
Note Source: Dissertation Abstracts International, Volume: 64-07, Section: B, page: 3465
Chairs: Robert Dean; Robert Thieke
Thesis (Ph.D.)--University of Florida, 2003
Field observations of rip currents have been one of the most difficult measurements to obtain owing to their hazardous nature and the fact that the rip current channels tend to migrate. This dissertation examines (1) innovative methods of obtaining nearshore bathymetry and current profiles within rip current channels, (2) the analysis of long-term video monitoring of rip current morphology at Duck, NC, and (3) the hydrodynamics (steady, sea breeze, infragravity (0.004--0.04 Hz), and very low frequency (<0.004 Hz)) and morphodynamics of a rip current field experiment (RIPEX) in Sand City, Monterey Bay, CA
In order to acquire proper measurements of nearshore morphology, traditional hydrographic surveying gear was placed in water-tight containers and mounted on a personal watercraft (PWC). The PWC system was tested and evaluated in Myrtle Beach, SC, and utilized on the beaches of California, Florida, Oregon, and Washington. An acoustic Doppler current profiler was added to the PWC for the acquisition of vertical velocity profiles within a rip current system, which was evaluated against fixed instruments
Three years of time-averaged video images from an Argus Station at Duck, NC were analyzed to gain insight on rip current channel behavior. Long-term observations suggest that rip current morphology is quasi-stable and is only modified during extreme storms (Hmo > 3 m) when there is a significant longshore current (V > 1m/s)
During spring 2001, a rip current field experiment (RIPEX) was carried out in which an extensive array of wave current sensors were deployed on a complex beach where rip currents were relatively persistent and plentiful. The measurements obtained during RIPEX allowed for a complete evaluation of rip current behavior through current, pressure, video, and bathymetric measurements, currently missing in the existing literature. Particular attention was focused on rip current pulsations, steady flows, sea breeze conditions, morphodynamics, vertical flow structure, and newly observed very low frequency motions
School code: 0070
Host Item Dissertation Abstracts International 64-07B
Subject Engineering, Marine and Ocean
Engineering, Civil
Physical Oceanography
Alt Author University of Florida
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