Aerial Imaging of Fluorescent Dye in the Near Shore

Clark, David B.; Lenain, Luc; Feddersen, Falk; Boss, Emmanuel; Guza, R. T.

doi:10.1175/jtech-d-13-00230.1

Cited by 41 publications

(64 citation statements)

References 22 publications

(20 reference statements)

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“…The 2.4. Inner-Shelf Dye Aerial Remote Sensing Novel aerial observations of nearsurface dye concentration were obtained from a small plane with a multispectral camera system and coupled global positioning and inertial navigation systems [Clark et al, 2014]. Two cameras captured images near the peak excitation and emission wavelengths of the fluorescent Rhodamine WT.…”

Section: Ib09 Experiments Methodsmentioning

confidence: 99%

“…The georeferenced aerial images are combined into mosaics and regridded onto a rectangular grid with 2 m 3 2 m lateral resolution. See Clark et al [2014] for details.…”

Section: Ib09 Experiments Methodsmentioning

confidence: 99%

“…The dye field was imaged from the shoreline to roughly 350 m offshore and from the release to roughly 3 km downstream. Pixels with excitation image brightness above an empirical threshold [Clark et al, 2014] owing to sun glitter or white foam from breaking waves are discarded. The surfzone is therefore often poorly resolved, and quantitative analyses of aerial images are confined to the inner-shelf.…”

Section: Ib09 Experiments Methodsmentioning

confidence: 99%

“…Here a novel aerial-based dye imaging system [Clark et al, 2014] is used to make high spatial resolution maps of inner-shelf dye spanning >3 km downstream of a 13 October continuous release. Combined aerial and in situ dye observations across the surfzone and inner-shelf are used to investigate far-downstream dye dilution, surfzone and inner-shelf dye mass balances, and cross-shore dye exchange.…”

Section: Introductionmentioning

confidence: 99%

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Surfzone to inner‐shelf exchange estimated from dye tracer balances

et al. 2015

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Surfzone and inner‐shelf tracer dispersion are observed at an approximately alongshore‐uniform beach. Fluorescent Rhodamine WT dye, released near the shoreline continuously for 6.5 h, is advected alongshore by breaking‐wave‐ and wind‐driven currents, and ejected offshore from the surfzone to the inner‐shelf by transient rip currents. Novel aerial‐based multispectral dye concentration images and in situ measurements of dye, waves, and currents provide tracer transport and dilution observations spanning about 350 m cross‐shore and 3 km alongshore. Downstream dilution of near‐shoreline dye follows power law decay with exponent −0.33, implying that a tenfold increase in alongshore distance reduces the concentration about 50%. Coupled surfzone and inner‐shelf dye mass balances close, and in 5 h, roughly half of the surfzone‐released dye is transported offshore to the inner‐shelf. Observed cross‐shore transports are parameterized well ( , best fit slope ) using a bulk exchange velocity and mean surfzone to inner‐shelf dye concentration difference. The best fit cross‐shore exchange velocity is similar to a temperature‐derived exchange velocity on another day with similar wave conditions. The magnitude and observed inner‐shelf dye length scales, time scales, and vertical structure indicate the dominance of transient rip currents in surfzone to inner‐shelf cross‐shore exchange during moderate waves at this alongshore‐uniform beach.

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Section: Ib09 Experiments Methodsmentioning

confidence: 99%

“…The georeferenced aerial images are combined into mosaics and regridded onto a rectangular grid with 2 m 3 2 m lateral resolution. See Clark et al [2014] for details.…”

Section: Ib09 Experiments Methodsmentioning

confidence: 99%

Section: Ib09 Experiments Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Surfzone to inner‐shelf exchange estimated from dye tracer balances

et al. 2015

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“…Grant et al (2005) analysis showed that alongshore flux of surfzone water is at least 50 to 300 times larger than the crossshore flux of surfzone water. Clark et al (2014) used fluorescent dye and aerial imaging technique to study the nearshore mixing. Feddersen (2007) studied breaking wave induced cross-shore tracer dispersion in the surfzone.…”

Section: Introductionmentioning

confidence: 99%

Application of Smoothed Particle Hydrodynamics (Sph) in Nearshore Mixing: A Comparison to Laboratory Data

Abolfathi

Pearson

2017

Int. Conf. Coastal. Eng.

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A weakly compressible smoothed particle hydrodynamics (WCSPH) method is used to simulate the nearshore flow hydrodynamics. The wave induced dispersion and diffusion are determined for monochromatic waves with significant wave height of 0.12 m and the wave period of 1.2 sec (Sop=5%) based on WCSPH wave dynamics. The hydrodynamics of WCSPH model are compared to the laboratory results obtained from series of LDA measurements. The overall mixing coefficients across the nearshore are determined from WCSPH hydrodynamics. The mixing coefficients obtained are compared with the values determined from a series of fluorometric studies performed in a large-scale facility in DHI, Denmark. The results show that the wave profiles are in good agreement with the experimental data. The WCSPH model is proven to be well capable of estimating the dispersion across the nearshore.

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The spatial‐temporal variability of air‐sea momentum fluxes observed at a tidal inlet

et al. 2015

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Coastal waters are an aerodynamically unique environment that has been little explored from an air-sea interaction point of view. Consequently, most studies must assume that open ocean-derived parameterizations of the air-sea momentum flux are representative of the nearshore wind forcing. Observations made at the New River Inlet in North Carolina, during the Riverine and Estuarine Transport experiment (RIVET), were used to evaluate the suitability of wind speed-dependent, wind stress parameterizations in coastal waters. As part of the field campaign, a small, agile research vessel was deployed to make high-resolution wind velocity measurements in and around the tidal inlet. The eddy covariance method was employed to recover direct estimates of the 10 m neutral atmospheric drag coefficient from the three-dimensional winds. Observations of wind stress angle, near-surface currents, and heat flux were used to analyze the cross-shore variability of wind stress steering off the mean wind azimuth. In general, for onshore winds above 5 m/s, the drag coefficient was observed to be two and a half times the predicted open ocean value. Significant wind stress steering is observed within 2 km of the inlet mouth, which is observed to be correlated with the horizontal current shear. Other mechanisms such as the reduction in wave celerity or depth-limited breaking could also play a role. It was determined that outside the influence of these typical coastal processes, the open ocean parameterizations generally represent the wind stress field. The nearshore stress variability has significant implications for observations and simulations of coastal transport, circulation, mixing, and general surf-zone dynamics.

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Aerial Imaging of Fluorescent Dye in the Near Shore

Cited by 41 publications

References 22 publications

Surfzone to inner‐shelf exchange estimated from dye tracer balances

Surfzone to inner‐shelf exchange estimated from dye tracer balances

Application of Smoothed Particle Hydrodynamics (Sph) in Nearshore Mixing: A Comparison to Laboratory Data

The spatial‐temporal variability of air‐sea momentum fluxes observed at a tidal inlet

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